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Ignore non-present page faults, since those cannot have reserved
bits set.
When running access.flat with "-cpu Haswell,phys-bits=36", the
number of trapped page faults goes down from 8872644 to 3978948.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-9-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Check guest physical address against its maximum, which depends on the
guest MAXPHYADDR. If the guest's physical address exceeds the
maximum (i.e. has reserved bits set), inject a guest page fault with
PFERR_RSVD_MASK set.
This has to be done both in the EPT violation and page fault paths, as
there are complications in both cases with respect to the computation
of the correct error code.
For EPT violations, unfortunately the only possibility is to emulate,
because the access type in the exit qualification might refer to an
access to a paging structure, rather than to the access performed by
the program.
Trapping page faults instead is needed in order to correct the error code,
but the access type can be obtained from the original error code and
passed to gva_to_gpa. The corrections required in the error code are
subtle. For example, imagine that a PTE for a supervisor page has a reserved
bit set. On a supervisor-mode access, the EPT violation path would trigger.
However, on a user-mode access, the processor will not notice the reserved
bit and not include PFERR_RSVD_MASK in the error code.
Co-developed-by: Mohammed Gamal <mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-8-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-7-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Allow vendor code to observe changes to MAXPHYADDR and start/stop
intercepting page faults.
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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We would like to introduce a callback to update the #PF intercept
when CPUID changes. Just reuse update_bp_intercept since VMX is
already using update_exception_bitmap instead of a bespoke function.
While at it, remove an unnecessary assignment in the SVM version,
which is already done in the caller (kvm_arch_vcpu_ioctl_set_guest_debug)
and has nothing to do with the exception bitmap.
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Intel processors of various generations have supported 36, 39, 46 or 52
bits for physical addresses. Until IceLake introduced MAXPHYADDR==52,
running on a machine with higher MAXPHYADDR than the guest more or less
worked, because software that relied on reserved address bits (like KVM)
generally used bit 51 as a marker and therefore the page faults where
generated anyway.
Unfortunately this is not true anymore if the host MAXPHYADDR is 52,
and this can cause problems when migrating from a MAXPHYADDR<52
machine to one with MAXPHYADDR==52. Typically, the latter are machines
that support 5-level page tables, so they can be identified easily from
the LA57 CPUID bit.
When that happens, the guest might have a physical address with reserved
bits set, but the host won't see that and trap it. Hence, we need
to check page faults' physical addresses against the guest's maximum
physical memory and if it's exceeded, we need to add the PFERR_RSVD_MASK
bits to the page fault error code.
This patch does this for the MMU's page walks. The next patches will
ensure that the correct exception and error code is produced whenever
no host-reserved bits are set in page table entries.
Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-4-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Also no point of it being inline since it's always called through
function pointers. So remove that.
Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-3-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch adds two helper functions that will be used to support virtualizing
MAXPHYADDR in both kvm-intel.ko and kvm.ko.
kvm_fixup_and_inject_pf_error() injects a page fault for a user-specified GVA,
while kvm_mmu_is_illegal_gpa() checks whether a GPA exceeds vCPU address limits.
Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200710154811.418214-2-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The mmu_check_root() check in fast_pgd_switch() seems to be
superfluous: when GPA is outside of the visible range
cached_root_available() will fail for non-direct roots
(as we can't have a matching one on the list) and we don't
seem to care for direct ones.
Also, raising #TF immediately when a non-existent GFN is written to CR3
doesn't seem to mach architectural behavior. Drop the check.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-10-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Make nSVM code resemble nVMX where nested_vmx_load_cr3() is used on
both guest->host and host->guest transitions. Also, we can now
eliminate unconditional kvm_mmu_reset_context() and speed things up.
Note, nVMX has two different paths: load_vmcs12_host_state() and
nested_vmx_restore_host_state() and the later is used to restore from
'partial' switch to L2, it always uses kvm_mmu_reset_context().
nSVM doesn't have this yet. Also, nested_svm_vmexit()'s return value
is almost always ignored nowadays.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-9-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Undesired triple fault gets injected to L1 guest on SVM when L2 is
launched with certain CR3 values. #TF is raised by mmu_check_root()
check in fast_pgd_switch() and the root cause is that when
kvm_set_cr3() is called from nested_prepare_vmcb_save() with NPT
enabled CR3 points to a nGPA so we can't check it with
kvm_is_visible_gfn().
Using generic kvm_set_cr3() when switching to nested guest is not
a great idea as we'll have to distinguish between 'real' CR3s and
'nested' CR3s to e.g. not call kvm_mmu_new_pgd() with nGPA. Following
nVMX implement nested-specific nested_svm_load_cr3() doing the job.
To support the change, nested_svm_load_cr3() needs to be re-ordered
with nested_svm_init_mmu_context().
Note: the current implementation is sub-optimal as we always do TLB
flush/MMU sync but this is still an improvement as we at least stop doing
kvm_mmu_reset_context().
Fixes: 7c390d350f8b ("kvm: x86: Add fast CR3 switch code path")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-8-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_mmu_new_pgd() refers to arch.mmu and at this point it still references
arch.guest_mmu while arch.root_mmu is expected.
Note, the change is effectively a nop: when !npt_enabled,
nested_svm_uninit_mmu_context() does nothing (as we don't do
nested_svm_init_mmu_context()) and with npt_enabled we don't
do kvm_set_cr3(). However, it will matter when we move the
call to kvm_mmu_new_pgd into nested_svm_load_cr3().
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-7-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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As a preparatory change for implementing nSVM-specific PGD switch
(following nVMX' nested_vmx_load_cr3()), introduce nested_svm_load_cr3()
instead of relying on kvm_set_cr3().
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Some operations in enter_svm_guest_mode() may fail, e.g. currently
we suppress kvm_set_cr3() return value. Prepare the code to proparate
errors.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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WARN_ON_ONCE(svm->nested.nested_run_pending) in nested_svm_vmexit()
will fire if nested_run_pending remains '1' but it doesn't really
need to, we are already failing and not going to run nested guest.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_init_shadow_mmu() was actually the only function that could be called
with different vcpu->arch.mmu values. Now that kvm_init_shadow_npt_mmu()
is separated from kvm_init_shadow_mmu(), we always know the MMU context
we need to use and there is no need to dereference vcpu->arch.mmu pointer.
Based on a patch by Vitaly Kuznetsov <vkuznets@redhat.com>.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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As a preparatory change for moving kvm_mmu_new_pgd() from
nested_prepare_vmcb_save() to nested_svm_init_mmu_context() split
kvm_init_shadow_npt_mmu() from kvm_init_shadow_mmu(). This also makes
the code look more like nVMX (kvm_init_shadow_ept_mmu()).
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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state_test/smm_test selftests are failing on AMD with:
"Unexpected result from KVM_GET_MSRS, r: 51 (failed MSR was 0x345)"
MSR_IA32_PERF_CAPABILITIES is an emulated MSR on Intel but it is not
known to AMD code, we can move the emulation to common x86 code. For
AMD, we basically just allow the host to read and write zero to the MSR.
Fixes: 27461da31089 ("KVM: x86/pmu: Support full width counting")
Suggested-by: Jim Mattson <jmattson@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710152559.1645827-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
2020-06-01) accidentally broke nVMX live migration from older version
by changing the userspace ABI. Restore it and, while at it, ensure
that vmx->nested.has_preemption_timer_deadline is always initialized
according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
Cc: Makarand Sonare <makarandsonare@google.com>
Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move x86's memory cache helpers to common KVM code so that they can be
reused by arm64 and MIPS in future patches.
Suggested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-16-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename the memory helpers that will soon be moved to common code and be
made globaly available via linux/kvm_host.h. "mmu" alone is not a
sufficient namespace for globally available KVM symbols.
Opportunistically add "nr_" in mmu_memory_cache_free_objects() to make
it clear the function returns the number of free objects, as opposed to
freeing existing objects.
Suggested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-14-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Don't bother filling the gfn array cache when the caller is a fully
direct MMU, i.e. won't need a gfn array for shadow pages.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-13-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Set __GFP_ZERO for the shadow page memory cache and drop the explicit
clear_page() from kvm_mmu_get_page(). This moves the cost of zeroing a
page to the allocation time of the physical page, i.e. when topping up
the memory caches, and thus avoids having to zero out an entire page
while holding mmu_lock.
Cc: Peter Feiner <pfeiner@google.com>
Cc: Peter Shier <pshier@google.com>
Cc: Junaid Shahid <junaids@google.com>
Cc: Jim Mattson <jmattson@google.com>
Suggested-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-12-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a gfp_zero flag to 'struct kvm_mmu_memory_cache' and use it to
control __GFP_ZERO instead of hardcoding a call to kmem_cache_zalloc().
A future patch needs such a flag for the __get_free_page() path, as
gfn arrays do not need/want the allocator to zero the memory. Convert
the kmem_cache paths to __GFP_ZERO now so as to avoid a weird and
inconsistent API in the future.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-11-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use separate caches for allocating shadow pages versus gfn arrays. This
sets the stage for specifying __GFP_ZERO when allocating shadow pages
without incurring extra cost for gfn arrays.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-10-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Clean up the minimums in mmu_topup_memory_caches() to document the
driving mechanisms behind the minimums. Now that encountering an empty
cache is unlikely to trigger BUG_ON(), it is less dangerous to be more
precise when defining the minimums.
For rmaps, the logic is 1 parent PTE per level, plus a single rmap, and
prefetched rmaps. The extra objects in the current '8 + PREFETCH'
minimum came about due to an abundance of paranoia in commit
c41ef344de212 ("KVM: MMU: increase per-vcpu rmap cache alloc size"),
i.e. it could have increased the minimum to 2 rmaps. Furthermore, the
unexpected extra rmap case was killed off entirely by commits
f759e2b4c728c ("KVM: MMU: avoid pte_list_desc running out in
kvm_mmu_pte_write") and f5a1e9f89504f ("KVM: MMU: remove call to
kvm_mmu_pte_write from walk_addr").
For the so called page cache, replace '8' with 2*PT64_ROOT_MAX_LEVEL.
The 2x multiplier is needed because the cache is used for both shadow
pages and gfn arrays for indirect MMUs.
And finally, for page headers, replace '4' with PT64_ROOT_MAX_LEVEL.
Note, KVM now supports 5-level paging, i.e. the old minimums that used a
baseline derived from 4-level paging were technically wrong. But, KVM
always allocates roots in a separate flow, e.g. it's impossible in the
current implementation to actually need 5 new shadow pages in a single
flow. Use PT64_ROOT_MAX_LEVEL unmodified instead of subtracting 1, as
the direct usage is likely more intuitive to uninformed readers, and the
inflated minimum is unlikely to affect functionality in practice.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-9-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Topup memory caches after walking the GVA->GPA translation during a
shadow page fault, there is no need to ensure the caches are full when
walking the GVA. As of commit f5a1e9f89504f ("KVM: MMU: remove call
to kvm_mmu_pte_write from walk_addr"), the FNAME(walk_addr) flow no
longer add rmaps via kvm_mmu_pte_write().
This avoids allocating memory in the case that the GVA is unmapped in
the guest, and also provides a paper trail of why/when the memory caches
need to be filled.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-8-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Avoid refilling the memory caches and potentially slow reclaim/swap when
handling a fast page fault, which does not need to allocate any new
objects.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-7-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Attempt to allocate a new object instead of crashing KVM (and likely the
kernel) if a memory cache is unexpectedly empty. Use GFP_ATOMIC for the
allocation as the caches are used while holding mmu_lock. The immediate
BUG_ON() makes the code unnecessarily explosive and led to confusing
minimums being used in the past, e.g. allocating 4 objects where 1 would
suffice.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-6-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Return errors directly from mmu_topup_memory_caches() instead of
branching to a label that does the same.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-5-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use "mc" for local variables to shorten line lengths and provide
consistent names, which will be especially helpful when some of the
helpers are moved to common KVM code in future patches.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-4-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop the "page" variants of the topup/free memory cache helpers, using
the existence of an associated kmem_cache to select the correct alloc
or free routine.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-3-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Track the kmem_cache used for non-page KVM MMU memory caches instead of
passing in the associated kmem_cache when filling the cache. This will
allow consolidating code and other cleanups.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-2-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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read/write_cr2() go throuh the paravirt XXL indirection, but nested VMX in
a XEN_PV guest is not supported.
Use the native variants.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Message-Id: <20200708195322.344731916@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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On guest exit MSR_GS_BASE contains whatever the guest wrote to it and the
first action after returning from the ASM code is to set it to the host
kernel value. This uses wrmsrl() which is interesting at least.
wrmsrl() is either using native_write_msr() or the paravirt variant. The
XEN_PV code is uninteresting as nested SVM in a XEN_PV guest does not work.
But native_write_msr() can be placed out of line by the compiler especially
when paravirtualization is enabled in the kernel configuration. The
function is marked notrace, but still can be probed if
CONFIG_KPROBE_EVENTS_ON_NOTRACE is enabled.
That would be a fatal problem as kprobe events use per-CPU variables which
are GS based and would be accessed with the guest GS. Depending on the GS
value this would either explode in colorful ways or lead to completely
undebugable data corruption.
Aside of that native_write_msr() contains a tracepoint which objtool
complains about as it is invoked from the noinstr section.
As this cannot run inside a XEN_PV guest there is no point in using
wrmsrl(). Use native_wrmsrl() instead which is just a plain native WRMSR
without tracing or anything else attached.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Juergen Gross <jgross@suse.com>
Message-Id: <20200708195322.244847377@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the functions which are inside the RCU off region into the
non-instrumentable text section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195322.144607767@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the functions which are inside the RCU off region into the
non-instrumentable text section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195322.037311579@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Entering guest mode is more or less the same as returning to user
space. From an instrumentation point of view both leave kernel mode and the
transition to guest or user mode reenables interrupts on the host. In user
mode an interrupt is served directly and in guest mode it causes a VM exit
which then handles or reinjects the interrupt.
The transition from guest mode or user mode to kernel mode disables
interrupts, which needs to be recorded in instrumentation to set the
correct state again.
This is important for e.g. latency analysis because otherwise the execution
time in guest or user mode would be wrongly accounted as interrupt disabled
and could trigger false positives.
Add hardirq tracing to guest enter/exit functions in the same way as it
is done in the user mode enter/exit code, respecting the RCU requirements.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195321.934715094@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Entering guest mode is more or less the same as returning to user
space. From an instrumentation point of view both leave kernel mode and the
transition to guest or user mode reenables interrupts on the host. In user
mode an interrupt is served directly and in guest mode it causes a VM exit
which then handles or reinjects the interrupt.
The transition from guest mode or user mode to kernel mode disables
interrupts, which needs to be recorded in instrumentation to set the
correct state again.
This is important for e.g. latency analysis because otherwise the execution
time in guest or user mode would be wrongly accounted as interrupt disabled
and could trigger false positives.
Add hardirq tracing to guest enter/exit functions in the same way as it
is done in the user mode enter/exit code, respecting the RCU requirements.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195321.822002354@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Context tracking for KVM happens way too early in the vcpu_run()
code. Anything after guest_enter_irqoff() and before guest_exit_irqoff()
cannot use RCU and should also be not instrumented.
The current way of doing this covers way too much code. Move it closer to
the actual vmenter/exit code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195321.724574345@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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To avoid complex and in some cases incorrect logic in
kvm_spec_ctrl_test_value, just try the guest's given value on the host
processor instead, and if it doesn't #GP, allow the guest to set it.
One such case is when host CPU supports STIBP mitigation
but doesn't support IBRS (as is the case with some Zen2 AMD cpus),
and in this case we were giving guest #GP when it tried to use STIBP
The reason why can can do the host test is that IA32_SPEC_CTRL msr is
passed to the guest, after the guest sets it to a non zero value
for the first time (due to performance reasons),
and as as result of this, it is pointless to emulate #GP condition on
this first access, in a different way than what the host CPU does.
This is based on a patch from Sean Christopherson, who suggested this idea.
Fixes: 6441fa6178f5 ("KVM: x86: avoid incorrect writes to host MSR_IA32_SPEC_CTRL")
Cc: stable@vger.kernel.org
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200708115731.180097-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In guest protected mode, if the current privilege level
is not 0 and the PCE flag in the CR4 register is cleared,
we will inject a #GP for RDPMC usage.
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20200708074409.39028-1-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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OVMF booted guest running on shadow pages crashes on TRIPLE FAULT after
enabling paging from SMM. The crash is triggered from mmu_check_root() and
is caused by kvm_is_visible_gfn() searching through memslots with as_id = 0
while vCPU may be in a different context (address space).
Introduce kvm_vcpu_is_visible_gfn() and use it from mmu_check_root().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200708140023.1476020-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_vcpu_after_set_cpuid()
kvm_x86_ops.vcpu_after_set_cpuid() is used to update vmx/svm specific
vcpu settings based on updated CPUID settings. So it's supposed to be
called after CPUIDs are updated, i.e., kvm_update_cpuid_runtime().
Currently, kvm_update_cpuid_runtime() only updates CPUID bits of OSXSAVE,
APIC, OSPKE, MWAIT, KVM_FEATURE_PV_UNHALT and CPUID(0xD,0).ebx and
CPUID(0xD, 1).ebx. None of them is consumed by vmx/svm's
update_vcpu_after_set_cpuid(). So there is no dependency between them.
Move kvm_x86_ops.vcpu_after_set_cpuid() into kvm_vcpu_after_set_cpuid() is
obviously more reasonable.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-6-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The name of callback cpuid_update() is misleading that it's not about
updating CPUID settings of vcpu but updating the configurations of vcpu
based on the CPUIDs. So rename it to vcpu_after_set_cpuid().
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-5-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Now there is no updating CPUID bits behavior in kvm_update_cpuid(),
rename it to kvm_vcpu_after_set_cpuid().
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-4-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Beside called in kvm_vcpu_ioctl_set_cpuid*(), kvm_update_cpuid() is also
called 5 places else in x86.c and 1 place else in lapic.c. All those 6
places only need the part of updating guest CPUIDs (OSXSAVE, OSPKE, APIC,
KVM_FEATURE_PV_UNHALT, ...) based on the runtime vcpu state, so extract
them as a separate kvm_update_cpuid_runtime().
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-3-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use kvm_check_cpuid() to validate if userspace provides legal cpuid
settings and call it before KVM take any action to update CPUID or
update vcpu states based on given CPUID settings.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-2-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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There is no dependencies between kvm_apic_set_version() and
kvm_update_cpuid() because kvm_apic_set_version() queries X2APIC CPUID bit,
which is not touched/changed by kvm_update_cpuid().
Obviously, kvm_apic_set_version() belongs to the category of updating
vcpu model.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200708065054.19713-9-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Only code cleanup and no functional change.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200708065054.19713-8-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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