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Unless explicitly told to do so (by passing 'clocksource=tsc' and
'tsc=stable:socket', and then jumping through some hoops concerning
potential CPU hotplug) Xen will never use TSC as its clocksource.
Hence, by default, a Xen guest will not see PVCLOCK_TSC_STABLE_BIT set
in either the primary or secondary pvclock memory areas. This has
led to bugs in some guest kernels which only become evident if
PVCLOCK_TSC_STABLE_BIT *is* set in the pvclocks. Hence, to support
such guests, give the VMM a new Xen HVM config flag to tell KVM to
forcibly clear the bit in the Xen pvclocks.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20231102162128.2353459-1-paul@xen.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
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'struct hv_vmcb_enlightenments' in VMCB only make sense when either
CONFIG_KVM_HYPERV or CONFIG_HYPERV is enabled.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-17-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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'hv_evmcs_vmptr'/'hv_evmcs_map'/'hv_evmcs' fields in 'struct nested_vmx'
should not be used when !CONFIG_KVM_HYPERV, hide them when
!CONFIG_KVM_HYPERV.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-16-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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There's a number of 'vmx->nested.hv_evmcs' accesses in nested.c, introduce
'nested_vmx_evmcs()' accessor to hide them all in !CONFIG_KVM_HYPERV case.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-15-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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In order to get rid of raw 'vmx->nested.hv_evmcs_vmptr' accesses when
!CONFIG_KVM_HYPERV, introduce a pair of helpers:
nested_vmx_is_evmptr12_valid() to check that eVMPTR points to a valid
address.
nested_vmx_is_evmptr12_valid() to check that eVMPTR either points to a
valid address or is in 'pending' port-migration state (meaning it is
supposed to be valid but the exact address wasn't acquired from guest's
memory yet).
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-14-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Hyper-V emulation in KVM is a fairly big chunk and in some cases it may be
desirable to not compile it in to reduce module sizes as well as the attack
surface. Introduce CONFIG_KVM_HYPERV option to make it possible.
Note, there's room for further nVMX/nSVM code optimizations when
!CONFIG_KVM_HYPERV, this will be done in follow-up patches.
Reorganize Makefile a bit so all CONFIG_HYPERV and CONFIG_KVM_HYPERV files
are grouped together.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-13-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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In preparation for making Hyper-V emulation optional, move Hyper-V specific
guest_cpuid_has_evmcs() to hyperv.h.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-12-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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To avoid overloading handle_vmclear() with Hyper-V specific details and to
prepare the code to making Hyper-V emulation optional, create a dedicated
nested_evmcs_handle_vmclear() helper.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-9-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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As a preparation to making Hyper-V emulation optional, introduce a helper
to handle pending KVM_REQ_HV_TLB_FLUSH requests.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-8-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Some Enlightened VMCS related code is needed both by Hyper-V on KVM and
KVM on Hyper-V. As a preparation to making Hyper-V emulation optional,
create dedicated 'hyperv_evmcs.{ch}' files which are used by both.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-7-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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As a preparation to making Hyper-V emulation optional, create a dedicated
kvm_hv_synic_has_vector() helper to avoid extra ifdefs in lapic.c.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-6-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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As a preparation to making Hyper-V emulation optional, create a dedicated
kvm_hv_synic_auto_eoi_set() helper to avoid extra ifdefs in lapic.c
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-5-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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hyperv.{ch} is currently a mix of stuff which is needed by both Hyper-V on
KVM and KVM on Hyper-V. As a preparation to making Hyper-V emulation
optional, put KVM-on-Hyper-V specific code into dedicated files.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-4-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Hyper-V partition assist page is used when KVM runs on top of Hyper-V and
is not used for Windows/Hyper-V guests on KVM, this means that 'hv_pa_pg'
placement in 'struct kvm_hv' is unfortunate. As a preparation to making
Hyper-V emulation optional, move 'hv_pa_pg' to 'struct kvm_arch' and put it
under CONFIG_HYPERV.
While on it, introduce hv_get_partition_assist_page() helper to allocate
partition assist page. Move the comment explaining why we use a single page
for all vCPUs from VMX and expand it a bit.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-3-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Saving a few bytes of memory per KVM VM is certainly great but what's more
important is the ability to see where the code accesses Xen emulation
context while CONFIG_KVM_XEN is not enabled. Currently, kvm_cpu_get_extint()
is the only such place and it is harmless: kvm_xen_has_interrupt() always
returns '0' when !CONFIG_KVM_XEN.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-2-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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The requested info will be stored in 'guest_xsave->region' referenced by
the incoming pointer "struct kvm_xsave *guest_xsave", thus there is no need
to explicitly use return void expression for a void function "static void
kvm_vcpu_ioctl_x86_get_xsave(...)". The issue is caught with [-Wpedantic].
Fixes: 2d287ec65e79 ("x86/fpu: Allow caller to constrain xfeatures when copying to uabi buffer")
Signed-off-by: Like Xu <likexu@tencent.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231007064019.17472-1-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Set .owner for all KVM-owned filed types so that the KVM module is pinned
until any files with callbacks back into KVM are completely freed. Using
"struct kvm" as a proxy for the module, i.e. keeping KVM-the-module alive
while there are active VMs, doesn't provide full protection.
Userspace can invoke delete_module() the instant the last reference to KVM
is put. If KVM itself puts the last reference, e.g. via kvm_destroy_vm(),
then it's possible for KVM to be preempted and deleted/unloaded before KVM
fully exits, e.g. when the task running kvm_destroy_vm() is scheduled back
in, it will jump to a code page that is no longer mapped.
Note, file types that can call into sub-module code, e.g. kvm-intel.ko or
kvm-amd.ko on x86, must use the module pointer passed to kvm_init(), not
THIS_MODULE (which points at kvm.ko). KVM assumes that if /dev/kvm is
reachable, e.g. VMs are active, then the vendor module is loaded.
To reduce the probability of forgetting to set .owner entirely, use
THIS_MODULE for stats files where KVM does not call back into vendor code.
This reverts commit 70375c2d8fa3fb9b0b59207a9c5df1e2e1205c10, and fixes
several other file types that have been buggy since their introduction.
Fixes: 70375c2d8fa3 ("Revert "KVM: set owner of cpu and vm file operations"")
Fixes: 3bcd0662d66f ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/all/20231010003746.GN800259@ZenIV
Link: https://lore.kernel.org/r/20231018204624.1905300-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Fix the comment about what can and cannot happen when mmu_unsync_pages_lock
is not help. The comment correctly mentions "clearing sp->unsync", but then
it talks about unsync going from 0 to 1.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-5-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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It is cheap to take tdp_mmu_pages_lock in all write-side critical sections.
We already do it all the time when zapping with read_lock(), so it is not
a problem to do it from the kvm_tdp_mmu_zap_all() path (aka
kvm_arch_flush_shadow_all(), aka VM destruction and MMU notifier release).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-4-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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The "bool shared" argument is more or less unnecessary in the
for_each_*_tdp_mmu_root_yield_safe() macros. Many users check for
the lock before calling it; all of them either call small functions
that do the check, or end up calling tdp_mmu_set_spte_atomic() and
tdp_mmu_iter_set_spte(). Add a few assertions to make up for the
lost check in for_each_*_tdp_mmu_root_yield_safe(), but even this
is probably overkill and mostly for documentation reasons.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-3-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Neither tdp_mmu_next_root nor kvm_tdp_mmu_put_root need to know
if the lock is taken for read or write. Either way, protection
is achieved via RCU and tdp_mmu_pages_lock. Remove the argument
and just assert that the lock is taken.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-2-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Re-check that the given SPTE is still a leaf and present SPTE after a
failed cmpxchg in clear_dirty_gfn_range(). clear_dirty_gfn_range()
intends to only operate on present leaf SPTEs, but that could change
after a failed cmpxchg.
A check for present was added in commit 3354ef5a592d ("KVM: x86/mmu:
Check for present SPTE when clearing dirty bit in TDP MMU") but the
check for leaf is still buried in tdp_root_for_each_leaf_pte() and does
not get rechecked on retry.
Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20231027172640.2335197-3-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Fix an off-by-1 error when passing in the range of pages to
kvm_mmu_try_split_huge_pages() during CLEAR_DIRTY_LOG. Specifically, end
is the last page that needs to be split (inclusive) so pass in `end + 1`
since kvm_mmu_try_split_huge_pages() expects the `end` to be
non-inclusive.
At worst this will cause a huge page to be write-protected instead of
eagerly split, which is purely a performance issue, not a correctness
issue. But even that is unlikely as it would require userspace pass in a
bitmap where the last page is the only 4K page on a huge page that needs
to be split.
Reported-by: Vipin Sharma <vipinsh@google.com>
Fixes: cb00a70bd4b7 ("KVM: x86/mmu: Split huge pages mapped by the TDP MMU during KVM_CLEAR_DIRTY_LOG")
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20231027172640.2335197-2-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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cpuid.c utilizes vmemdup_user() and array_size() to copy two userspace
arrays. This, currently, does not check for an overflow.
Use the new wrapper vmemdup_array_user() to copy the arrays more safely,
as vmemdup_user() doesn't check for overflow.
Note, KVM explicitly checks the number of entries before duplicating the
array, i.e. adding the overflow check should be a glorified nop.
Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Link: https://lore.kernel.org/r/20231102181526.43279-2-pstanner@redhat.com
[sean: call out that KVM pre-checks the number of entries]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Explicitly track emulated counter events instead of using the common
counter value that's shared with the hardware counter owned by perf.
Bumping the common counter requires snapshotting the pre-increment value
in order to detect overflow from emulation, and the snapshot approach is
inherently flawed.
Snapshotting the previous counter at every increment assumes that there is
at most one emulated counter event per emulated instruction (or rather,
between checks for KVM_REQ_PMU). That's mostly holds true today because
KVM only emulates (branch) instructions retired, but the approach will
fall apart if KVM ever supports event types that don't have a 1:1
relationship with instructions.
And KVM already has a relevant bug, as handle_invalid_guest_state()
emulates multiple instructions without checking KVM_REQ_PMU, i.e. could
miss an overflow event due to clobbering pmc->prev_counter. Not checking
KVM_REQ_PMU is problematic in both cases, but at least with the emulated
counter approach, the resulting behavior is delayed overflow detection,
as opposed to completely lost detection.
Tracking the emulated count fixes another bug where the snapshot approach
can signal spurious overflow due to incorporating both the emulated count
and perf's count in the check, i.e. if overflow is detected by perf, then
KVM's emulation will also incorrectly signal overflow. Add a comment in
the related code to call out the need to process emulated events *after*
pausing the perf event (big kudos to Mingwei for figuring out that
particular wrinkle).
Cc: Mingwei Zhang <mizhang@google.com>
Cc: Roman Kagan <rkagan@amazon.de>
Cc: Jim Mattson <jmattson@google.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Like Xu <like.xu.linux@gmail.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20231103230541.352265-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Update a PMC's sample period in pmc_write_counter() to deduplicate code
across all callers of pmc_write_counter(). Opportunistically move
pmc_write_counter() into pmc.c now that it's doing more work. WRMSR isn't
such a hot path that an extra CALL+RET pair will be problematic, and the
order of function definitions needs to be changed anyways, i.e. now is a
convenient time to eat the churn.
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20231103230541.352265-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Remove code that unnecessarily clears event_count and need_cleanup in
kvm_pmu_init(), the entire kvm_pmu is zeroed just a few lines earlier.
Vendor code doesn't set event_count or need_cleanup during .init(), and
if either VMX or SVM did set those fields it would be a flagrant bug.
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20231103230541.352265-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Drop kvm_vcpu_reset()'s call to kvm_pmu_reset(), the call is performed
only for RESET, which is really just the same thing as vCPU creation,
and kvm_arch_vcpu_create() *just* called kvm_pmu_init(), i.e. there can't
possibly be any work to do.
Unlike Intel, AMD's amd_pmu_refresh() does fill all_valid_pmc_idx even if
guest CPUID is empty, but everything that is at all dynamic is guaranteed
to be '0'/NULL, e.g. it should be impossible for KVM to have already
created a perf event.
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20231103230541.352265-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Stop all counters and release all perf events before refreshing the vPMU,
i.e. before reconfiguring the vPMU to respond to changes in the vCPU
model.
Clear need_cleanup in kvm_pmu_reset() as well so that KVM doesn't
prematurely stop counters, e.g. if KVM enters the guest and enables
counters before the vCPU is scheduled out.
Cc: stable@vger.kernel.org
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20231103230541.352265-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Move the common (or at least "ignored") aspects of resetting the vPMU to
common x86 code, along with the stop/release helpers that are no used only
by the common pmu.c.
There is no need to manually handle fixed counters as all_valid_pmc_idx
tracks both fixed and general purpose counters, and resetting the vPMU is
far from a hot path, i.e. the extra bit of overhead to the PMC from the
index is a non-issue.
Zero fixed_ctr_ctrl in common code even though it's Intel specific.
Ensuring it's zero doesn't harm AMD/SVM in any way, and stopping the fixed
counters via all_valid_pmc_idx, but not clearing the associated control
bits, would be odd/confusing.
Make the .reset() hook optional as SVM no longer needs vendor specific
handling.
Cc: stable@vger.kernel.org
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20231103230541.352265-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Instruction with %rip-relative address operand is one byte shorter than
its absolute address counterpart and is also compatible with position
independent executable (-fpie) build.
No functional changes intended.
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20231031075312.47525-1-ubizjak@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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When vNMI is enabled, rely entirely on hardware to correctly handle NMI
blocking, i.e. don't intercept IRET to detect when NMIs are no longer
blocked. KVM already correctly ignores svm->nmi_masked when vNMI is
enabled, so the effect of the bug is essentially an unnecessary VM-Exit.
KVM intercepts IRET for two reasons:
- To track NMI masking to be able to know at any point of time if NMI
is masked.
- To track NMI windows (to inject another NMI after the guest executes
IRET, i.e. unblocks NMIs)
When vNMI is enabled, both cases are handled by hardware:
- NMI masking state resides in int_ctl.V_NMI_BLOCKING and can be read by
KVM at will.
- Hardware automatically "injects" pending virtual NMIs when virtual NMIs
become unblocked.
However, even though pending a virtual NMI for hardware to handle is the
most common way to synthesize a guest NMI, KVM may still directly inject
an NMI via when KVM is handling two "simultaneous" NMIs (see comments in
process_nmi() for details on KVM's simultaneous NMI handling). Per AMD's
APM, hardware sets the BLOCKING flag when software directly injects an NMI
as well, i.e. KVM doesn't need to manually mark vNMIs as blocked:
If Event Injection is used to inject an NMI when NMI Virtualization is
enabled, VMRUN sets V_NMI_MASK in the guest state.
Note, it's still possible that KVM could trigger a spurious IRET VM-Exit.
When running a nested guest, KVM disables vNMI for L2 and thus will enable
IRET interception (in both vmcb01 and vmcb02) while running L2 reason. If
a nested VM-Exit happens before L2 executes IRET, KVM can end up running
L1 with vNMI enable and IRET intercepted. This is also a benign bug, and
even less likely to happen, i.e. can be safely punted to a future fix.
Fixes: fa4c027a7956 ("KVM: x86: Add support for SVM's Virtual NMI")
Link: https://lore.kernel.org/all/ZOdnuDZUd4mevCqe@google.como
Cc: Santosh Shukla <santosh.shukla@amd.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Santosh Shukla <santosh.shukla@amd.com>
Link: https://lore.kernel.org/r/20231018192021.1893261-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Add a sanity check that FLUSHBYASID is available if SEV is supported in
hardware, as SEV (and beyond) guests are bound to a single ASID, i.e. KVM
can't "flush" by assigning a new, fresh ASID to the guest. If FLUSHBYASID
isn't supported for some bizarre reason, KVM would completely fail to do
TLB flushes for SEV+ guests (see pre_svm_run() and pre_sev_run()).
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20231018193617.1895752-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Advertise support for FLUSHBYASID when nested SVM is enabled, as KVM can
always emulate flushing TLB entries for a vmcb12 ASID, e.g. by running L2
with a new, fresh ASID in vmcb02. Some modern hypervisors, e.g. VMWare
Workstation 17, require FLUSHBYASID support and will refuse to run if it's
not present.
Punt on proper support, as "Honor L1's request to flush an ASID on nested
VMRUN" is one of the TODO items in the (incomplete) list of issues that
need to be addressed in order for KVM to NOT do a full TLB flush on every
nested SVM transition (see nested_svm_transition_tlb_flush()).
Reported-by: Stefan Sterz <s.sterz@proxmox.com>
Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231018194104.1896415-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Revert KVM's made-up consistency check on SVM's TLB control. The APM says
that unsupported encodings are reserved, but the APM doesn't state that
VMRUN checks for a supported encoding. Unless something is called out
in "Canonicalization and Consistency Checks" or listed as MBZ (Must Be
Zero), AMD behavior is typically to let software shoot itself in the foot.
This reverts commit 174a921b6975ef959dd82ee9e8844067a62e3ec1.
Fixes: 174a921b6975 ("nSVM: Check for reserved encodings of TLB_CONTROL in nested VMCB")
Reported-by: Stefan Sterz <s.sterz@proxmox.com>
Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com
Cc: stable@vger.kernel.org
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231018194104.1896415-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Don't force a masterclock update when a vCPU synchronizes to the current
TSC generation, e.g. when userspace hotplugs a pre-created vCPU into the
VM. Unnecessarily updating the masterclock is undesirable as it can cause
kvmclock's time to jump, which is particularly painful on systems with a
stable TSC as kvmclock _should_ be fully reliable on such systems.
The unexpected time jumps are due to differences in the TSC=>nanoseconds
conversion algorithms between kvmclock and the host's CLOCK_MONOTONIC_RAW
(the pvclock algorithm is inherently lossy). When updating the
masterclock, KVM refreshes the "base", i.e. moves the elapsed time since
the last update from the kvmclock/pvclock algorithm to the
CLOCK_MONOTONIC_RAW algorithm. Synchronizing kvmclock with
CLOCK_MONOTONIC_RAW is the lesser of evils when the TSC is unstable, but
adds no real value when the TSC is stable.
Prior to commit 7f187922ddf6 ("KVM: x86: update masterclock values on TSC
writes"), KVM did NOT force an update when synchronizing a vCPU to the
current generation.
commit 7f187922ddf6b67f2999a76dcb71663097b75497
Author: Marcelo Tosatti <mtosatti@redhat.com>
Date: Tue Nov 4 21:30:44 2014 -0200
KVM: x86: update masterclock values on TSC writes
When the guest writes to the TSC, the masterclock TSC copy must be
updated as well along with the TSC_OFFSET update, otherwise a negative
tsc_timestamp is calculated at kvm_guest_time_update.
Once "if (!vcpus_matched && ka->use_master_clock)" is simplified to
"if (ka->use_master_clock)", the corresponding "if (!ka->use_master_clock)"
becomes redundant, so remove the do_request boolean and collapse
everything into a single condition.
Before that, KVM only re-synced the masterclock if the masterclock was
enabled or disabled Note, at the time of the above commit, VMX
synchronized TSC on *guest* writes to MSR_IA32_TSC:
case MSR_IA32_TSC:
kvm_write_tsc(vcpu, msr_info);
break;
which is why the changelog specifically says "guest writes", but the bug
that was being fixed wasn't unique to guest write, i.e. a TSC write from
the host would suffer the same problem.
So even though KVM stopped synchronizing on guest writes as of commit
0c899c25d754 ("KVM: x86: do not attempt TSC synchronization on guest
writes"), simply reverting commit 7f187922ddf6 is not an option. Figuring
out how a negative tsc_timestamp could be computed requires a bit more
sleuthing.
In kvm_write_tsc() (at the time), except for KVM's "less than 1 second"
hack, KVM snapshotted the vCPU's current TSC *and* the current time in
nanoseconds, where kvm->arch.cur_tsc_nsec is the current host kernel time
in nanoseconds:
ns = get_kernel_ns();
...
if (usdiff < USEC_PER_SEC &&
vcpu->arch.virtual_tsc_khz == kvm->arch.last_tsc_khz) {
...
} else {
/*
* We split periods of matched TSC writes into generations.
* For each generation, we track the original measured
* nanosecond time, offset, and write, so if TSCs are in
* sync, we can match exact offset, and if not, we can match
* exact software computation in compute_guest_tsc()
*
* These values are tracked in kvm->arch.cur_xxx variables.
*/
kvm->arch.cur_tsc_generation++;
kvm->arch.cur_tsc_nsec = ns;
kvm->arch.cur_tsc_write = data;
kvm->arch.cur_tsc_offset = offset;
matched = false;
pr_debug("kvm: new tsc generation %llu, clock %llu\n",
kvm->arch.cur_tsc_generation, data);
}
...
/* Keep track of which generation this VCPU has synchronized to */
vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation;
vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
Note that the above creates a new generation and sets "matched" to false!
But because kvm_track_tsc_matching() looks for matched+1, i.e. doesn't
require the vCPU that creates the new generation to match itself, KVM
would immediately compute vcpus_matched as true for VMs with a single vCPU.
As a result, KVM would skip the masterlock update, even though a new TSC
generation was created:
vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
atomic_read(&vcpu->kvm->online_vcpus));
if (vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC)
if (!ka->use_master_clock)
do_request = 1;
if (!vcpus_matched && ka->use_master_clock)
do_request = 1;
if (do_request)
kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
On hardware without TSC scaling support, vcpu->tsc_catchup is set to true
if the guest TSC frequency is faster than the host TSC frequency, even if
the TSC is otherwise stable. And for that mode, kvm_guest_time_update(),
by way of compute_guest_tsc(), uses vcpu->arch.this_tsc_nsec, a.k.a. the
kernel time at the last TSC write, to compute the guest TSC relative to
kernel time:
static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
{
u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.this_tsc_nsec,
vcpu->arch.virtual_tsc_mult,
vcpu->arch.virtual_tsc_shift);
tsc += vcpu->arch.this_tsc_write;
return tsc;
}
Except the "kernel_ns" passed to compute_guest_tsc() isn't the current
kernel time, it's the masterclock snapshot!
spin_lock(&ka->pvclock_gtod_sync_lock);
use_master_clock = ka->use_master_clock;
if (use_master_clock) {
host_tsc = ka->master_cycle_now;
kernel_ns = ka->master_kernel_ns;
}
spin_unlock(&ka->pvclock_gtod_sync_lock);
if (vcpu->tsc_catchup) {
u64 tsc = compute_guest_tsc(v, kernel_ns);
if (tsc > tsc_timestamp) {
adjust_tsc_offset_guest(v, tsc - tsc_timestamp);
tsc_timestamp = tsc;
}
}
And so when KVM skips the masterclock update after a TSC write, i.e. after
a new TSC generation is started, the "kernel_ns-vcpu->arch.this_tsc_nsec"
is *guaranteed* to generate a negative value, because this_tsc_nsec was
captured after ka->master_kernel_ns.
Forcing a masterclock update essentially fudged around that problem, but
in a heavy handed way that introduced undesirable side effects, i.e.
unnecessarily forces a masterclock update when a new vCPU joins the party
via hotplug.
Note, KVM forces masterclock updates in other weird ways that are also
likely unnecessary, e.g. when establishing a new Xen shared info page and
when userspace creates a brand new vCPU. But the Xen thing is firmly a
separate mess, and there are no known userspace VMMs that utilize kvmclock
*and* create new vCPUs after the VM is up and running. I.e. the other
issues are future problems.
Reported-by: Dongli Zhang <dongli.zhang@oracle.com>
Closes: https://lore.kernel.org/all/20230926230649.67852-1-dongli.zhang@oracle.com
Fixes: 7f187922ddf6 ("KVM: x86: update masterclock values on TSC writes")
Cc: David Woodhouse <dwmw2@infradead.org>
Reviewed-by: Dongli Zhang <dongli.zhang@oracle.com>
Tested-by: Dongli Zhang <dongli.zhang@oracle.com>
Link: https://lore.kernel.org/r/20231018195638.1898375-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Use a switch statement with macro-generated case statements to handle
translating feature flags in order to reduce the probability of runtime
errors due to copy+paste goofs, to make compile-time errors easier to
debug, and to make the code more readable.
E.g. the compiler won't directly generate an error for duplicate if
statements
if (x86_feature == X86_FEATURE_SGX1)
return KVM_X86_FEATURE_SGX1;
else if (x86_feature == X86_FEATURE_SGX2)
return KVM_X86_FEATURE_SGX1;
and so instead reverse_cpuid_check() will fail due to the untranslated
entry pointing at a Linux-defined leaf, which provides practically no
hint as to what is broken
arch/x86/kvm/reverse_cpuid.h:108:2: error: call to __compiletime_assert_450 declared with 'error' attribute:
BUILD_BUG_ON failed: x86_leaf == CPUID_LNX_4
BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
^
whereas duplicate case statements very explicitly point at the offending
code:
arch/x86/kvm/reverse_cpuid.h:125:2: error: duplicate case value '361'
KVM_X86_TRANSLATE_FEATURE(SGX2);
^
arch/x86/kvm/reverse_cpuid.h:124:2: error: duplicate case value '360'
KVM_X86_TRANSLATE_FEATURE(SGX1);
^
And without macros, the opposite type of copy+paste goof doesn't generate
any error at compile-time, e.g. this yields no complaints:
case X86_FEATURE_SGX1:
return KVM_X86_FEATURE_SGX1;
case X86_FEATURE_SGX2:
return KVM_X86_FEATURE_SGX1;
Note, __feature_translate() is forcibly inlined and the feature is known
at compile-time, so the code generation between an if-elif sequence and a
switch statement should be identical.
Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20231024001636.890236-2-jmattson@google.com
[sean: use a macro, rewrite changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
The low five bits {INTEL_PSFD, IPRED_CTRL, RRSBA_CTRL, DDPD_U, BHI_CTRL}
advertise the availability of specific bits in IA32_SPEC_CTRL. Since KVM
dynamically determines the legal IA32_SPEC_CTRL bits for the underlying
hardware, the hard work has already been done. Just let userspace know
that a guest can use these IA32_SPEC_CTRL bits.
The sixth bit (MCDT_NO) states that the processor does not exhibit MXCSR
Configuration Dependent Timing (MCDT) behavior. This is an inherent
property of the physical processor that is inherited by the virtual
CPU. Pass that information on to userspace.
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20231024001636.890236-1-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Don't enable KVM_WERROR by default for x86-64 builds as KVM's one-off
-Werror enabling is *mostly* superseded by the kernel-wide WERROR, and
enabling KVM_WERROR by default can cause problems for developers working
on other subsystems. E.g. subsystems that have a "zero W=1 regressions"
rule can inadvertently build KVM with -Werror and W=1, and end up with
build failures that are completely uninteresting to the developer (W=1 is
prone to false positives, especially on older compilers).
Keep KVM_WERROR as there are combinations where enabling WERROR isn't
feasible, e.g. the default FRAME_WARN=1024 on i386 builds generates a
non-zero number of warnings and thus errors, and there are far too many
warnings throughout the kernel to enable WERROR with W=1 (building KVM
with -Werror is desirable (with a sane compiler) as W=1 does generate
useful warnings).
Opportunistically drop the dependency on !COMPILE_TEST as it's completely
meaningless (it was copied from i195's -Werror Kconfig), as the kernel's
WERROR is explicitly *enabled* for COMPILE_TEST=y kernel's, i.e. enabling
-Werror is obviosly not dependent on COMPILE_TEST=n.
Reported-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/all/20231006205415.3501535-1-kuba@kernel.org
Link: https://lore.kernel.org/r/20231018151906.1841689-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Declare the kvm_x86_ops hooks used to wire up paravirt TLB flushes when
running under Hyper-V if and only if CONFIG_HYPERV!=n. Wrapping yet more
code with IS_ENABLED(CONFIG_HYPERV) eliminates a handful of conditional
branches, and makes it super obvious why the hooks *might* be valid.
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231018192325.1893896-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
When querying whether or not a vCPU "is" running in kernel mode, directly
get the CPL if the vCPU is the currently loaded vCPU. In scenarios where
a guest is profiled via perf-kvm, querying vcpu->arch.preempted_in_kernel
from kvm_guest_state() is wrong if vCPU is actively running, i.e. isn't
scheduled out due to being preempted and so preempted_in_kernel is stale.
This affects perf/core's ability to accurately tag guest RIP with
PERF_RECORD_MISC_GUEST_{KERNEL|USER} and record it in the sample. This
causes perf/tool to fail to connect the vCPU RIPs to the guest kernel
space symbols when parsing these samples due to incorrect PERF_RECORD_MISC
flags:
Before (perf-report of a cpu-cycles sample):
1.23% :58945 [unknown] [u] 0xffffffff818012e0
After:
1.35% :60703 [kernel.vmlinux] [g] asm_exc_page_fault
Note, checking preempted_in_kernel in kvm_arch_vcpu_in_kernel() is awful
as nothing in the API's suggests that it's safe to use if and only if the
vCPU was preempted. That can be cleaned up in the future, for now just
fix the glaring correctness bug.
Note #2, checking vcpu->preempted is NOT safe, as getting the CPL on VMX
requires VMREAD, i.e. is correct if and only if the vCPU is loaded. If
the target vCPU *was* preempted, then it can be scheduled back in after
the check on vcpu->preempted in kvm_vcpu_on_spin(), i.e. KVM could end up
trying to do VMREAD on a VMCS that isn't loaded on the current pCPU.
Signed-off-by: Like Xu <likexu@tencent.com>
Fixes: e1bfc24577cc ("KVM: Move x86's perf guest info callbacks to generic KVM")
Link: https://lore.kernel.org/r/20231123075818.12521-1-likexu@tencent.com
[sean: massage changelong, add Fixes]
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Use the governed feature framework to track if Linear Address Masking (LAM)
is "enabled", i.e. if LAM can be used by the guest.
Using the framework to avoid the relative expensive call guest_cpuid_has()
during cr3 and vmexit handling paths for LAM.
No functional change intended.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-14-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
LAM is enumerated by CPUID.7.1:EAX.LAM[bit 26]. Advertise the feature to
userspace and enable it as the final step after the LAM virtualization
support for supervisor and user pointers.
SGX LAM support is not advertised yet. SGX LAM support is enumerated in
SGX's own CPUID and there's no hard requirement that it must be supported
when LAM is reported in CPUID leaf 0x7.
Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Jingqi Liu <jingqi.liu@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-13-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Add support to allow guests to set the new CR3 control bits for Linear
Address Masking (LAM) and add implementation to get untagged address for
user pointers.
LAM modifies the canonical check for 64-bit linear addresses, allowing
software to use the masked/ignored address bits for metadata. Hardware
masks off the metadata bits before using the linear addresses to access
memory. LAM uses two new CR3 non-address bits, LAM_U48 (bit 62) and
LAM_U57 (bit 61), to configure LAM for user pointers. LAM also changes
VMENTER to allow both bits to be set in VMCS's HOST_CR3 and GUEST_CR3 for
virtualization.
When EPT is on, CR3 is not trapped by KVM and it's up to the guest to set
any of the two LAM control bits. However, when EPT is off, the actual CR3
used by the guest is generated from the shadow MMU root which is different
from the CR3 that is *set* by the guest, and KVM needs to manually apply
any active control bits to VMCS's GUEST_CR3 based on the cached CR3 *seen*
by the guest.
KVM manually checks guest's CR3 to make sure it points to a valid guest
physical address (i.e. to support smaller MAXPHYSADDR in the guest). Extend
this check to allow the two LAM control bits to be set. After check, LAM
bits of guest CR3 will be stripped off to extract guest physical address.
In case of nested, for a guest which supports LAM, both VMCS12's HOST_CR3
and GUEST_CR3 are allowed to have the new LAM control bits set, i.e. when
L0 enters L1 to emulate a VMEXIT from L2 to L1 or when L0 enters L2
directly. KVM also manually checks VMCS12's HOST_CR3 and GUEST_CR3 being
valid physical address. Extend such check to allow the new LAM control bits
too.
Note, LAM doesn't have a global control bit to turn on/off LAM completely,
but purely depends on hardware's CPUID to determine it can be enabled or
not. That means, when EPT is on, even when KVM doesn't expose LAM to guest,
the guest can still set LAM control bits in CR3 w/o causing problem. This
is an unfortunate virtualization hole. KVM could choose to intercept CR3 in
this case and inject fault but this would hurt performance when running a
normal VM w/o LAM support. This is undesirable. Just choose to let the
guest do such illegal thing as the worst case is guest being killed when
KVM eventually find out such illegal behaviour and that the guest is
misbehaving.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-12-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Add support to allow guests to set the new CR4 control bit for LAM and add
implementation to get untagged address for supervisor pointers.
LAM modifies the canonicality check applied to 64-bit linear addresses for
data accesses, allowing software to use of the untranslated address bits for
metadata and masks the metadata bits before using them as linear addresses
to access memory. LAM uses CR4.LAM_SUP (bit 28) to configure and enable LAM
for supervisor pointers. It also changes VMENTER to allow the bit to be set
in VMCS's HOST_CR4 and GUEST_CR4 to support virtualization. Note CR4.LAM_SUP
is allowed to be set even not in 64-bit mode, but it will not take effect
since LAM only applies to 64-bit linear addresses.
Move CR4.LAM_SUP out of CR4_RESERVED_BITS, its reservation depends on vcpu
supporting LAM or not. Leave it intercepted to prevent guest from setting
the bit if LAM is not exposed to guest as well as to avoid vmread every time
when KVM fetches its value, with the expectation that guest won't toggle the
bit frequently.
Set CR4.LAM_SUP bit in the emulated IA32_VMX_CR4_FIXED1 MSR for guests to
allow guests to enable LAM for supervisor pointers in nested VMX operation.
Hardware is not required to do TLB flush when CR4.LAM_SUP toggled, KVM
doesn't need to emulate TLB flush based on it. There's no other features
or vmx_exec_controls connection, and no other code needed in
{kvm,vmx}_set_cr4().
Skip address untag for instruction fetches (which includes branch targets),
operand of INVLPG instructions, and implicit system accesses, all of which
are not subject to untagging. Note, get_untagged_addr() isn't invoked for
implicit system accesses as there is no reason to do so, but check the
flag anyways for documentation purposes.
Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-11-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Stub in vmx_get_untagged_addr() and wire up calls from the emulator (via
get_untagged_addr()) and "direct" calls from various VM-Exit handlers in
VMX where LAM untagging is supposed to be applied. Defer implementing
the guts of vmx_get_untagged_addr() to future patches purely to make the
changes easier to consume.
LAM is active only for 64-bit linear addresses and several types of
accesses are exempted.
- Cases need to untag address (handled in get_vmx_mem_address())
Operand(s) of VMX instructions and INVPCID.
Operand(s) of SGX ENCLS.
- Cases LAM doesn't apply to (no change needed)
Operand of INVLPG.
Linear address in INVPCID descriptor.
Linear address in INVVPID descriptor.
BASEADDR specified in SECS of ECREATE.
Note:
- LAM doesn't apply to write to control registers or MSRs
- LAM masking is applied before walking page tables, i.e. the faulting
linear address in CR2 doesn't contain the metadata.
- The guest linear address saved in VMCS doesn't contain metadata.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-10-binbin.wu@linux.intel.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
|
|
Introduce a new interface get_untagged_addr() to kvm_x86_ops to untag
the metadata from linear address. Call the interface in linearization
of instruction emulator for 64-bit mode.
When enabled feature like Intel Linear Address Masking (LAM) or AMD Upper
Address Ignore (UAI), linear addresses may be tagged with metadata that
needs to be dropped prior to canonicality checks, i.e. the metadata is
ignored.
Introduce get_untagged_addr() to kvm_x86_ops to hide the vendor specific
code, as sadly LAM and UAI have different semantics. Pass the emulator
flags to allow vendor specific implementation to precisely identify the
access type (LAM doesn't untag certain accesses).
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-9-binbin.wu@linux.intel.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Remove kvm_vcpu_is_illegal_gpa() and use !kvm_vcpu_is_legal_gpa() instead.
The "illegal" helper actually predates the "legal" helper, the only reason
the "illegal" variant wasn't removed by commit 4bda0e97868a ("KVM: x86:
Add a helper to check for a legal GPA") was to avoid code churn. Now that
CR3 has a dedicated helper, there are fewer callers, and so the code churn
isn't that much of a deterrent.
No functional change intended.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-8-binbin.wu@linux.intel.com
[sean: provide a bit of history in the changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add and use kvm_vcpu_is_legal_cr3() to check CR3's legality to provide
a clear distinction between CR3 and GPA checks. This will allow exempting
bits from kvm_vcpu_is_legal_cr3() without affecting general GPA checks,
e.g. for upcoming features that will use high bits in CR3 for feature
enabling.
No functional change intended.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-7-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Drop non-PA bits when getting GFN for guest's PGD with the maximum theoretical
mask for guest MAXPHYADDR.
Do it unconditionally because it's harmless for 32-bit guests, querying 64-bit
mode would be more expensive, and for EPT the mask isn't tied to guest mode.
Using PT_BASE_ADDR_MASK would be technically wrong (PAE paging has 64-bit
elements _except_ for CR3, which has only 32 valid bits), it wouldn't matter
in practice though.
Opportunistically use GENMASK_ULL() to define __PT_BASE_ADDR_MASK.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-6-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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