summaryrefslogtreecommitdiff
path: root/virt
AgeCommit message (Collapse)AuthorFilesLines
2022-05-02KVM: Add max_vcpus field in common 'struct kvm'Sean Christopherson1-1/+2
For TDX guests, the maximum number of vcpus needs to be specified when the TDX guest VM is initialized (creating the TDX data corresponding to TDX guest) before creating vcpu. It needs to record the maximum number of vcpus on VM creation (KVM_CREATE_VM) and return error if the number of vcpus exceeds it Because there is already max_vcpu member in arm64 struct kvm_arch, move it to common struct kvm and initialize it to KVM_MAX_VCPUS before kvm_arch_init_vm() instead of adding it to x86 struct kvm_arch. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> Message-Id: <e53234cdee6a92357d06c80c03d77c19cdefb804.1646422845.git.isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-29Merge branch 'kvm-fixes-for-5.18-rc5' into HEADPaolo Bonzini1-0/+1
Fixes for (relatively) old bugs, to be merged in both the -rc and next development trees: * Fix potential races when walking host page table * Fix bad user ABI for KVM_EXIT_SYSTEM_EVENT * Fix shadow page table leak when KVM runs nested
2022-04-29KVM: fix bad user ABI for KVM_EXIT_SYSTEM_EVENTPaolo Bonzini1-0/+1
When KVM_EXIT_SYSTEM_EVENT was introduced, it included a flags member that at the time was unused. Unfortunately this extensibility mechanism has several issues: - x86 is not writing the member, so it would not be possible to use it on x86 except for new events - the member is not aligned to 64 bits, so the definition of the uAPI struct is incorrect for 32- on 64-bit userspace. This is a problem for RISC-V, which supports CONFIG_KVM_COMPAT, but fortunately usage of flags was only introduced in 5.18. Since padding has to be introduced, place a new field in there that tells if the flags field is valid. To allow further extensibility, in fact, change flags to an array of 16 values, and store how many of the values are valid. The availability of the new ndata field is tied to a system capability; all architectures are changed to fill in the field. To avoid breaking compilation of userspace that was using the flags field, provide a userspace-only union to overlap flags with data[0]. The new field is placed at the same offset for both 32- and 64-bit userspace. Cc: Will Deacon <will@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Peter Gonda <pgonda@google.com> Cc: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reported-by: kernel test robot <lkp@intel.com> Message-Id: <20220422103013.34832-1-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-21KVM: SEV: add cache flush to solve SEV cache incoherency issuesMingwei Zhang1-3/+24
Flush the CPU caches when memory is reclaimed from an SEV guest (where reclaim also includes it being unmapped from KVM's memslots). Due to lack of coherency for SEV encrypted memory, failure to flush results in silent data corruption if userspace is malicious/broken and doesn't ensure SEV guest memory is properly pinned and unpinned. Cache coherency is not enforced across the VM boundary in SEV (AMD APM vol.2 Section 15.34.7). Confidential cachelines, generated by confidential VM guests have to be explicitly flushed on the host side. If a memory page containing dirty confidential cachelines was released by VM and reallocated to another user, the cachelines may corrupt the new user at a later time. KVM takes a shortcut by assuming all confidential memory remain pinned until the end of VM lifetime. Therefore, KVM does not flush cache at mmu_notifier invalidation events. Because of this incorrect assumption and the lack of cache flushing, malicous userspace can crash the host kernel: creating a malicious VM and continuously allocates/releases unpinned confidential memory pages when the VM is running. Add cache flush operations to mmu_notifier operations to ensure that any physical memory leaving the guest VM get flushed. In particular, hook mmu_notifier_invalidate_range_start and mmu_notifier_release events and flush cache accordingly. The hook after releasing the mmu lock to avoid contention with other vCPUs. Cc: stable@vger.kernel.org Suggested-by: Sean Christpherson <seanjc@google.com> Reported-by: Mingwei Zhang <mizhang@google.com> Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220421031407.2516575-4-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-21KVM: SPDX style and spelling fixesTom Rix3-4/+4
SPDX comments use use /* */ style comments in headers anad // style comments in .c files. Also fix two spelling mistakes. Signed-off-by: Tom Rix <trix@redhat.com> Message-Id: <20220410153840.55506-1-trix@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-21KVM: Initialize debugfs_dentry when a VM is created to avoid NULL derefSean Christopherson1-6/+6
Initialize debugfs_entry to its semi-magical -ENOENT value when the VM is created. KVM's teardown when VM creation fails is kludgy and calls kvm_uevent_notify_change() and kvm_destroy_vm_debugfs() even if KVM never attempted kvm_create_vm_debugfs(). Because debugfs_entry is zero initialized, the IS_ERR() checks pass and KVM derefs a NULL pointer. BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1068b1067 P4D 1068b1067 PUD 1068b0067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 871 Comm: repro Not tainted 5.18.0-rc1+ #825 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__dentry_path+0x7b/0x130 Call Trace: <TASK> dentry_path_raw+0x42/0x70 kvm_uevent_notify_change.part.0+0x10c/0x200 [kvm] kvm_put_kvm+0x63/0x2b0 [kvm] kvm_dev_ioctl+0x43a/0x920 [kvm] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x31/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xae </TASK> Modules linked in: kvm_intel kvm irqbypass Fixes: a44a4cc1c969 ("KVM: Don't create VM debugfs files outside of the VM directory") Cc: stable@vger.kernel.org Cc: Marc Zyngier <maz@kernel.org> Cc: Oliver Upton <oupton@google.com> Reported-by: syzbot+df6fbbd2ee39f21289ef@syzkaller.appspotmail.com Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Oliver Upton <oupton@google.com> Message-Id: <20220415004622.2207751-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-08Merge tag 'kvmarm-fixes-5.18-1' of ↵Paolo Bonzini1-2/+8
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm64 fixes for 5.18, take #1 - Some PSCI fixes after introducing PSCIv1.1 and SYSTEM_RESET2 - Fix the MMU write-lock not being taken on THP split - Fix mixed-width VM handling - Fix potential UAF when debugfs registration fails - Various selftest updates for all of the above
2022-04-07KVM: Don't create VM debugfs files outside of the VM directoryOliver Upton1-2/+8
Unfortunately, there is no guarantee that KVM was able to instantiate a debugfs directory for a particular VM. To that end, KVM shouldn't even attempt to create new debugfs files in this case. If the specified parent dentry is NULL, debugfs_create_file() will instantiate files at the root of debugfs. For arm64, it is possible to create the vgic-state file outside of a VM directory, the file is not cleaned up when a VM is destroyed. Nonetheless, the corresponding struct kvm is freed when the VM is destroyed. Nip the problem in the bud for all possible errant debugfs file creations by initializing kvm->debugfs_dentry to -ENOENT. In so doing, debugfs_create_file() will fail instead of creating the file in the root directory. Cc: stable@kernel.org Fixes: 929f45e32499 ("kvm: no need to check return value of debugfs_create functions") Signed-off-by: Oliver Upton <oupton@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220406235615.1447180-2-oupton@google.com
2022-04-06KVM: avoid NULL pointer dereference in kvm_dirty_ring_pushPaolo Bonzini1-1/+1
kvm_vcpu_release() will call kvm_dirty_ring_free(), freeing ring->dirty_gfns and setting it to NULL. Afterwards, it calls kvm_arch_vcpu_destroy(). However, if closing the file descriptor races with KVM_RUN in such away that vcpu->arch.st.preempted == 0, the following call stack leads to a NULL pointer dereference in kvm_dirty_run_push(): mark_page_dirty_in_slot+0x192/0x270 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3171 kvm_steal_time_set_preempted arch/x86/kvm/x86.c:4600 [inline] kvm_arch_vcpu_put+0x34e/0x5b0 arch/x86/kvm/x86.c:4618 vcpu_put+0x1b/0x70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:211 vmx_free_vcpu+0xcb/0x130 arch/x86/kvm/vmx/vmx.c:6985 kvm_arch_vcpu_destroy+0x76/0x290 arch/x86/kvm/x86.c:11219 kvm_vcpu_destroy arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 [inline] The fix is to release the dirty page ring after kvm_arch_vcpu_destroy has run. Reported-by: Qiuhao Li <qiuhao@sysec.org> Reported-by: Gaoning Pan <pgn@zju.edu.cn> Reported-by: Yongkang Jia <kangel@zju.edu.cn> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-02KVM: Remove dirty handling from gfn_to_pfn_cache completelyDavid Woodhouse1-33/+8
It isn't OK to cache the dirty status of a page in internal structures for an indefinite period of time. Any time a vCPU exits the run loop to userspace might be its last; the VMM might do its final check of the dirty log, flush the last remaining dirty pages to the destination and complete a live migration. If we have internal 'dirty' state which doesn't get flushed until the vCPU is finally destroyed on the source after migration is complete, then we have lost data because that will escape the final copy. This problem already exists with the use of kvm_vcpu_unmap() to mark pages dirty in e.g. VMX nesting. Note that the actual Linux MM already considers the page to be dirty since we have a writeable mapping of it. This is just about the KVM dirty logging. For the nesting-style use cases (KVM_GUEST_USES_PFN) we will need to track which gfn_to_pfn_caches have been used and explicitly mark the corresponding pages dirty before returning to userspace. But we would have needed external tracking of that anyway, rather than walking the full list of GPCs to find those belonging to this vCPU which are dirty. So let's rely *solely* on that external tracking, and keep it simple rather than laying a tempting trap for callers to fall into. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220303154127.202856-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-02KVM: Use enum to track if cached PFN will be used in guest and/or hostSean Christopherson1-7/+7
Replace the guest_uses_pa and kernel_map booleans in the PFN cache code with a unified enum/bitmask. Using explicit names makes it easier to review and audit call sites. Opportunistically add a WARN to prevent passing garbage; instantating a cache without declaring its usage is either buggy or pointless. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220303154127.202856-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-02KVM: Don't actually set a request when evicting vCPUs for GFN cache invdSean Christopherson2-8/+13
Don't actually set a request bit in vcpu->requests when making a request purely to force a vCPU to exit the guest. Logging a request but not actually consuming it would cause the vCPU to get stuck in an infinite loop during KVM_RUN because KVM would see the pending request and bail from VM-Enter to service the request. Note, it's currently impossible for KVM to set KVM_REQ_GPC_INVALIDATE as nothing in KVM is wired up to set guest_uses_pa=true. But, it'd be all too easy for arch code to introduce use of kvm_gfn_to_pfn_cache_init() without implementing handling of the request, especially since getting test coverage of MMU notifier interaction with specific KVM features usually requires a directed test. Opportunistically rename gfn_to_pfn_cache_invalidate_start()'s wake_vcpus to evict_vcpus. The purpose of the request is to get vCPUs out of guest mode, it's supposed to _avoid_ waking vCPUs that are blocking. Opportunistically rename KVM_REQ_GPC_INVALIDATE to be more specific as to what it wants to accomplish, and to genericize the name so that it can used for similar but unrelated scenarios, should they arise in the future. Add a comment and documentation to explain why the "no action" request exists. Add compile-time assertions to help detect improper usage. Use the inner assertless helper in the one s390 path that makes requests without a hardcoded request. Cc: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220223165302.3205276-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-02KVM: avoid double put_page with gfn-to-pfn cacheDavid Woodhouse1-0/+1
If the cache's user host virtual address becomes invalid, there is still a path from kvm_gfn_to_pfn_cache_refresh() where __release_gpc() could release the pfn but the gpc->pfn field has not been overwritten with an error value. If this happens, kvm_gfn_to_pfn_cache_unmap will call put_page again on the same page. Cc: stable@vger.kernel.org Fixes: 982ed0de4753 ("KVM: Reinstate gfn_to_pfn_cache with invalidation support") Signed-off-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-29Revert "KVM: set owner of cpu and vm file operations"David Matlack1-4/+2
This reverts commit 3d3aab1b973b01bd2a1aa46307e94a1380b1d802. Now that the KVM module's lifetime is tied to kvm.users_count, there is no need to also tie it's lifetime to the lifetime of the VM and vCPU file descriptors. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: David Matlack <dmatlack@google.com> Message-Id: <20220303183328.1499189-3-dmatlack@google.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-29KVM: Prevent module exit until all VMs are freedDavid Matlack1-0/+13
Tie the lifetime the KVM module to the lifetime of each VM via kvm.users_count. This way anything that grabs a reference to the VM via kvm_get_kvm() cannot accidentally outlive the KVM module. Prior to this commit, the lifetime of the KVM module was tied to the lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU file descriptors by their respective file_operations "owner" field. This approach is insufficient because references grabbed via kvm_get_kvm() do not prevent closing any of the aforementioned file descriptors. This fixes a long standing theoretical bug in KVM that at least affects async page faults. kvm_setup_async_pf() grabs a reference via kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing prevents the VM file descriptor from being closed and the KVM module from being unloaded before this callback runs. Fixes: af585b921e5d ("KVM: Halt vcpu if page it tries to access is swapped out") Fixes: 3d3aab1b973b ("KVM: set owner of cpu and vm file operations") Cc: stable@vger.kernel.org Suggested-by: Ben Gardon <bgardon@google.com> [ Based on a patch from Ben implemented for Google's kernel. ] Signed-off-by: David Matlack <dmatlack@google.com> Message-Id: <20220303183328.1499189-2-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-11KVM: compat: riscv: Prevent KVM_COMPAT from being selectedGuo Ren1-1/+1
Current riscv doesn't support the 32bit KVM API. Let's make it clear by not selecting KVM_COMPAT. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Anup Patel <anup@brainfault.org> Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Anup Patel <anup@brainfault.org>
2022-03-08KVM: use __vcalloc for very large allocationsPaolo Bonzini1-2/+2
Allocations whose size is related to the memslot size can be arbitrarily large. Do not use kvzalloc/kvcalloc, as those are limited to "not crazy" sizes that fit in 32 bits. Cc: stable@vger.kernel.org Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls") Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-05Merge branch 'kvm-bugfixes' into HEADPaolo Bonzini1-3/+1
Merge bugfixes from 5.17 before merging more tricky work.
2022-03-01KVM: Drop kvm_reload_remote_mmus(), open code request in x86 usersSean Christopherson1-5/+0
Remove the generic kvm_reload_remote_mmus() and open code its functionality into the two x86 callers. x86 is (obviously) the only architecture that uses the hook, and is also the only architecture that uses KVM_REQ_MMU_RELOAD in a way that's consistent with the name. That will change in a future patch, as x86's usage when zapping a single shadow page x86 doesn't actually _need_ to reload all vCPUs' MMUs, only MMUs whose root is being zapped actually need to be reloaded. s390 also uses KVM_REQ_MMU_RELOAD, but for a slightly different purpose. Drop the generic code in anticipation of implementing s390 and x86 arch specific requests, which will allow dropping KVM_REQ_MMU_RELOAD entirely. Opportunistically reword the x86 TDP MMU comment to avoid making references to functions (and requests!) when possible, and to remove the rather ambiguous "this". No functional change intended. Cc: Ben Gardon <bgardon@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Ben Gardon <bgardon@google.com> Message-Id: <20220225182248.3812651-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-25KVM: Move VM's worker kthreads back to the original cgroup before exiting.Vipin Sharma1-1/+21
VM worker kthreads can linger in the VM process's cgroup for sometime after KVM terminates the VM process. KVM terminates the worker kthreads by calling kthread_stop() which waits on the 'exited' completion, triggered by exit_mm(), via mm_release(), in do_exit() during the kthread's exit. However, these kthreads are removed from the cgroup using the cgroup_exit() which happens after the exit_mm(). Therefore, A VM process can terminate in between the exit_mm() and cgroup_exit() calls, leaving only worker kthreads in the cgroup. Moving worker kthreads back to the original cgroup (kthreadd_task's cgroup) makes sure that the cgroup is empty as soon as the main VM process is terminated. Signed-off-by: Vipin Sharma <vipinsh@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220222054848.563321-1-vipinsh@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-17KVM: Fix lockdep false negative during host resumeWanpeng Li1-3/+1
I saw the below splatting after the host suspended and resumed. WARNING: CPU: 0 PID: 2943 at kvm/arch/x86/kvm/../../../virt/kvm/kvm_main.c:5531 kvm_resume+0x2c/0x30 [kvm] CPU: 0 PID: 2943 Comm: step_after_susp Tainted: G W IOE 5.17.0-rc3+ #4 RIP: 0010:kvm_resume+0x2c/0x30 [kvm] Call Trace: <TASK> syscore_resume+0x90/0x340 suspend_devices_and_enter+0xaee/0xe90 pm_suspend.cold+0x36b/0x3c2 state_store+0x82/0xf0 kernfs_fop_write_iter+0x1b6/0x260 new_sync_write+0x258/0x370 vfs_write+0x33f/0x510 ksys_write+0xc9/0x160 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae lockdep_is_held() can return -1 when lockdep is disabled which triggers this warning. Let's use lockdep_assert_not_held() which can detect incorrect calls while holding a lock and it also avoids false negatives when lockdep is disabled. Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1644920142-81249-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: Remove unused "kvm" of kvm_make_vcpu_request()Jinrong Liang1-5/+4
The "struct kvm *kvm" parameter of kvm_make_vcpu_request() is not used, so remove it. No functional change intended. Signed-off-by: Jinrong Liang <cloudliang@tencent.com> Message-Id: <20220125095909.38122-19-cloudliang@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-28Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2-9/+7
Pull kvm fixes from Paolo Bonzini: "Two larger x86 series: - Redo incorrect fix for SEV/SMAP erratum - Windows 11 Hyper-V workaround Other x86 changes: - Various x86 cleanups - Re-enable access_tracking_perf_test - Fix for #GP handling on SVM - Fix for CPUID leaf 0Dh in KVM_GET_SUPPORTED_CPUID - Fix for ICEBP in interrupt shadow - Avoid false-positive RCU splat - Enable Enlightened MSR-Bitmap support for real ARM: - Correctly update the shadow register on exception injection when running in nVHE mode - Correctly use the mm_ops indirection when performing cache invalidation from the page-table walker - Restrict the vgic-v3 workaround for SEIS to the two known broken implementations Generic code changes: - Dead code cleanup" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (43 commits) KVM: eventfd: Fix false positive RCU usage warning KVM: nVMX: Allow VMREAD when Enlightened VMCS is in use KVM: nVMX: Implement evmcs_field_offset() suitable for handle_vmread() KVM: nVMX: Rename vmcs_to_field_offset{,_table} KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER KVM: nVMX: Also filter MSR_IA32_VMX_TRUE_PINBASED_CTLS when eVMCS selftests: kvm: check dynamic bits against KVM_X86_XCOMP_GUEST_SUPP KVM: x86: add system attribute to retrieve full set of supported xsave states KVM: x86: Add a helper to retrieve userspace address from kvm_device_attr selftests: kvm: move vm_xsave_req_perm call to amx_test KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time KVM: x86: Update vCPU's runtime CPUID on write to MSR_IA32_XSS KVM: x86: Keep MSR_IA32_XSS unchanged for INIT KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2} KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 KVM: selftests: Don't skip L2's VMCALL in SMM test for SVM guest KVM: x86: Check .flags in kvm_cpuid_check_equal() too KVM: x86: Forcibly leave nested virt when SMM state is toggled KVM: SVM: drop unnecessary code in svm_hv_vmcb_dirty_nested_enlightenments() KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real ...
2022-01-28KVM: eventfd: Fix false positive RCU usage warningHou Wenlong1-4/+4
Fix the following false positive warning: ============================= WARNING: suspicious RCU usage 5.16.0-rc4+ #57 Not tainted ----------------------------- arch/x86/kvm/../../../virt/kvm/eventfd.c:484 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by fc_vcpu 0/330: #0: ffff8884835fc0b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x88/0x6f0 [kvm] #1: ffffc90004c0bb68 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0x600/0x1860 [kvm] #2: ffffc90004c0c1d0 (&kvm->irq_srcu){....}-{0:0}, at: kvm_notify_acked_irq+0x36/0x180 [kvm] stack backtrace: CPU: 26 PID: 330 Comm: fc_vcpu 0 Not tainted 5.16.0-rc4+ Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x44/0x57 kvm_notify_acked_gsi+0x6b/0x70 [kvm] kvm_notify_acked_irq+0x8d/0x180 [kvm] kvm_ioapic_update_eoi+0x92/0x240 [kvm] kvm_apic_set_eoi_accelerated+0x2a/0xe0 [kvm] handle_apic_eoi_induced+0x3d/0x60 [kvm_intel] vmx_handle_exit+0x19c/0x6a0 [kvm_intel] vcpu_enter_guest+0x66e/0x1860 [kvm] kvm_arch_vcpu_ioctl_run+0x438/0x7f0 [kvm] kvm_vcpu_ioctl+0x38a/0x6f0 [kvm] __x64_sys_ioctl+0x89/0xc0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Since kvm_unregister_irq_ack_notifier() does synchronize_srcu(&kvm->irq_srcu), kvm->irq_ack_notifier_list is protected by kvm->irq_srcu. In fact, kvm->irq_srcu SRCU read lock is held in kvm_notify_acked_irq(), making it a false positive warning. So use hlist_for_each_entry_srcu() instead of hlist_for_each_entry_rcu(). Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Hou Wenlong <houwenlong93@linux.alibaba.com> Message-Id: <f98bac4f5052bad2c26df9ad50f7019e40434512.1643265976.git.houwenlong.hwl@antgroup.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-26Revert "KVM: SVM: avoid infinite loop on NPF from bad address"Sean Christopherson1-1/+0
Revert a completely broken check on an "invalid" RIP in SVM's workaround for the DecodeAssists SMAP errata. kvm_vcpu_gfn_to_memslot() obviously expects a gfn, i.e. operates in the guest physical address space, whereas RIP is a virtual (not even linear) address. The "fix" worked for the problematic KVM selftest because the test identity mapped RIP. Fully revert the hack instead of trying to translate RIP to a GPA, as the non-SEV case is now handled earlier, and KVM cannot access guest page tables to translate RIP. This reverts commit e72436bc3a5206f95bb384e741154166ddb3202e. Fixes: e72436bc3a52 ("KVM: SVM: avoid infinite loop on NPF from bad address") Reported-by: Liam Merwick <liam.merwick@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Message-Id: <20220120010719.711476-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-24KVM: remove async parameter of hva_to_pfn_remapped()Xianting Tian1-4/+3
The async parameter of hva_to_pfn_remapped() is not used, so remove it. Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> Message-Id: <20220124020456.156386-1-xianting.tian@linux.alibaba.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-22Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-3/+2
Pull more kvm updates from Paolo Bonzini: "Generic: - selftest compilation fix for non-x86 - KVM: avoid warning on s390 in mark_page_dirty x86: - fix page write-protection bug and improve comments - use binary search to lookup the PMU event filter, add test - enable_pmu module parameter support for Intel CPUs - switch blocked_vcpu_on_cpu_lock to raw spinlock - cleanups of blocked vCPU logic - partially allow KVM_SET_CPUID{,2} after KVM_RUN (5.16 regression) - various small fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (46 commits) docs: kvm: fix WARNINGs from api.rst selftests: kvm/x86: Fix the warning in lib/x86_64/processor.c selftests: kvm/x86: Fix the warning in pmu_event_filter_test.c kvm: selftests: Do not indent with spaces kvm: selftests: sync uapi/linux/kvm.h with Linux header selftests: kvm: add amx_test to .gitignore KVM: SVM: Nullify vcpu_(un)blocking() hooks if AVIC is disabled KVM: SVM: Move svm_hardware_setup() and its helpers below svm_x86_ops KVM: SVM: Drop AVIC's intermediate avic_set_running() helper KVM: VMX: Don't do full kick when handling posted interrupt wakeup KVM: VMX: Fold fallback path into triggering posted IRQ helper KVM: VMX: Pass desired vector instead of bool for triggering posted IRQ KVM: VMX: Don't do full kick when triggering posted interrupt "fails" KVM: SVM: Skip AVIC and IRTE updates when loading blocking vCPU KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption KVM: SVM: Remove unnecessary APICv/AVIC update in vCPU unblocking path KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers ...
2022-01-19KVM: Move x86 VMX's posted interrupt list_head to vcpu_vmxSean Christopherson1-2/+0
Move the seemingly generic block_vcpu_list from kvm_vcpu to vcpu_vmx, and rename the list and all associated variables to clarify that it tracks the set of vCPU that need to be poked on a posted interrupt to the wakeup vector. The list is not used to track _all_ vCPUs that are blocking, and the term "blocked" can be misleading as it may refer to a blocking condition in the host or the guest, where as the PI wakeup case is specifically for the vCPUs that are actively blocking from within the guest. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211208015236.1616697-7-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-19KVM: Drop unused kvm_vcpu.pre_pcpu fieldSean Christopherson1-1/+0
Remove kvm_vcpu.pre_pcpu as it no longer has any users. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211208015236.1616697-6-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-19KVM: avoid warning on s390 in mark_page_dirtyChristian Borntraeger1-0/+2
Avoid warnings on s390 like [ 1801.980931] CPU: 12 PID: 117600 Comm: kworker/12:0 Tainted: G E 5.17.0-20220113.rc0.git0.32ce2abb03cf.300.fc35.s390x+next #1 [ 1801.980938] Workqueue: events irqfd_inject [kvm] [...] [ 1801.981057] Call Trace: [ 1801.981060] [<000003ff805f0f5c>] mark_page_dirty_in_slot+0xa4/0xb0 [kvm] [ 1801.981083] [<000003ff8060e9fe>] adapter_indicators_set+0xde/0x268 [kvm] [ 1801.981104] [<000003ff80613c24>] set_adapter_int+0x64/0xd8 [kvm] [ 1801.981124] [<000003ff805fb9aa>] kvm_set_irq+0xc2/0x130 [kvm] [ 1801.981144] [<000003ff805f8d86>] irqfd_inject+0x76/0xa0 [kvm] [ 1801.981164] [<0000000175e56906>] process_one_work+0x1fe/0x470 [ 1801.981173] [<0000000175e570a4>] worker_thread+0x64/0x498 [ 1801.981176] [<0000000175e5ef2c>] kthread+0x10c/0x110 [ 1801.981180] [<0000000175de73c8>] __ret_from_fork+0x40/0x58 [ 1801.981185] [<000000017698440a>] ret_from_fork+0xa/0x40 when writing to a guest from an irqfd worker as long as we do not have the dirty ring. Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com> Reluctantly-acked-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20220113122924.740496-1-borntraeger@linux.ibm.com> Fixes: 2efd61a608b0 ("KVM: Warn if mark_page_dirty() is called without an active vCPU") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-16Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds8-475/+1028
Pull kvm updates from Paolo Bonzini: "RISCV: - Use common KVM implementation of MMU memory caches - SBI v0.2 support for Guest - Initial KVM selftests support - Fix to avoid spurious virtual interrupts after clearing hideleg CSR - Update email address for Anup and Atish ARM: - Simplification of the 'vcpu first run' by integrating it into KVM's 'pid change' flow - Refactoring of the FP and SVE state tracking, also leading to a simpler state and less shared data between EL1 and EL2 in the nVHE case - Tidy up the header file usage for the nvhe hyp object - New HYP unsharing mechanism, finally allowing pages to be unmapped from the Stage-1 EL2 page-tables - Various pKVM cleanups around refcounting and sharing - A couple of vgic fixes for bugs that would trigger once the vcpu xarray rework is merged, but not sooner - Add minimal support for ARMv8.7's PMU extension - Rework kvm_pgtable initialisation ahead of the NV work - New selftest for IRQ injection - Teach selftests about the lack of default IPA space and page sizes - Expand sysreg selftest to deal with Pointer Authentication - The usual bunch of cleanups and doc update s390: - fix sigp sense/start/stop/inconsistency - cleanups x86: - Clean up some function prototypes more - improved gfn_to_pfn_cache with proper invalidation, used by Xen emulation - add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery - completely remove potential TOC/TOU races in nested SVM consistency checks - update some PMCs on emulated instructions - Intel AMX support (joint work between Thomas and Intel) - large MMU cleanups - module parameter to disable PMU virtualization - cleanup register cache - first part of halt handling cleanups - Hyper-V enlightened MSR bitmap support for nested hypervisors Generic: - clean up Makefiles - introduce CONFIG_HAVE_KVM_DIRTY_RING - optimize memslot lookup using a tree - optimize vCPU array usage by converting to xarray" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (268 commits) x86/fpu: Fix inline prefix warnings selftest: kvm: Add amx selftest selftest: kvm: Move struct kvm_x86_state to header selftest: kvm: Reorder vcpu_load_state steps for AMX kvm: x86: Disable interception for IA32_XFD on demand x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state() kvm: selftests: Add support for KVM_CAP_XSAVE2 kvm: x86: Add support for getting/setting expanded xstate buffer x86/fpu: Add uabi_size to guest_fpu kvm: x86: Add CPUID support for Intel AMX kvm: x86: Add XCR0 support for Intel AMX kvm: x86: Disable RDMSR interception of IA32_XFD_ERR kvm: x86: Emulate IA32_XFD_ERR for guest kvm: x86: Intercept #NM for saving IA32_XFD_ERR x86/fpu: Prepare xfd_err in struct fpu_guest kvm: x86: Add emulation for IA32_XFD x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation kvm: x86: Enable dynamic xfeatures at KVM_SET_CPUID2 x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM x86/fpu: Add guest support to xfd_enable_feature() ...
2022-01-13Merge tag 'perf_core_for_v5.17_rc1' of ↵Linus Torvalds1-0/+44
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf updates from Borislav Petkov: "Cleanup of the perf/kvm interaction." * tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Drop guest callback (un)register stubs KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y KVM: arm64: Convert to the generic perf callbacks KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c KVM: Move x86's perf guest info callbacks to generic KVM KVM: x86: More precisely identify NMI from guest when handling PMI KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable perf/core: Use static_call to optimize perf_guest_info_callbacks perf: Force architectures to opt-in to guest callbacks perf: Add wrappers for invoking guest callbacks perf/core: Rework guest callbacks to prepare for static_call support perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv perf: Stop pretending that perf can handle multiple guest callbacks KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest KVM: x86: Register perf callbacks after calling vendor's hardware_setup() perf: Protect perf_guest_cbs with RCU
2022-01-07KVM: Reinstate gfn_to_pfn_cache with invalidation supportDavid Woodhouse7-27/+395
This can be used in two modes. There is an atomic mode where the cached mapping is accessed while holding the rwlock, and a mode where the physical address is used by a vCPU in guest mode. For the latter case, an invalidation will wake the vCPU with the new KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any caches it still needs to access before entering guest mode again. Only one vCPU can be targeted by the wake requests; it's simple enough to make it wake all vCPUs or even a mask but I don't see a use case for that additional complexity right now. Invalidation happens from the invalidate_range_start MMU notifier, which needs to be able to sleep in order to wake the vCPU and wait for it. This means that revalidation potentially needs to "wait" for the MMU operation to complete and the invalidate_range_end notifier to be invoked. Like the vCPU when it takes a page fault in that period, we just spin — fixing that in a future patch by implementing an actual *wait* may be another part of shaving this particularly hirsute yak. As noted in the comments in the function itself, the only case where the invalidate_range_start notifier is expected to be called *without* being able to sleep is when the OOM reaper is killing the process. In that case, we expect the vCPU threads already to have exited, and thus there will be nothing to wake, and no reason to wait. So we clear the KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly if there actually *was* anything to wake up. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20211210163625.2886-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-07KVM: Warn if mark_page_dirty() is called without an active vCPUDavid Woodhouse2-10/+6
The various kvm_write_guest() and mark_page_dirty() functions must only ever be called in the context of an active vCPU, because if dirty ring tracking is enabled it may simply oops when kvm_get_running_vcpu() returns NULL for the vcpu and then kvm_dirty_ring_get() dereferences it. This oops was reported by "butt3rflyh4ck" <butterflyhuangxx@gmail.com> in https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/ That actual bug will be fixed under separate cover but this warning should help to prevent new ones from being added. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20211210163625.2886-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-09KVM: Add Makefile.kvm for common files, use it for x86David Woodhouse1-0/+13
Splitting kvm_main.c out into smaller and better-organized files is slightly non-trivial when it involves editing a bunch of per-arch KVM makefiles. Provide virt/kvm/Makefile.kvm for them to include. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Acked-by: Marc Zyngier <maz@kernel.org> Message-Id: <20211121125451.9489-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-09KVM: Introduce CONFIG_HAVE_KVM_DIRTY_RINGDavid Woodhouse2-2/+5
I'd like to make the build include dirty_ring.c based on whether the arch wants it or not. That's a whole lot simpler if there's a config symbol instead of doing it implicitly on KVM_DIRTY_LOG_PAGE_OFFSET being set to something non-zero. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20211121125451.9489-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Add helpers to wake/query blocking vCPUSean Christopherson2-7/+3
Add helpers to wake and query a blocking vCPU. In addition to providing nice names, the helpers reduce the probability of KVM neglecting to use kvm_arch_vcpu_get_wait(). No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-20-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Don't redo ktime_get() when calculating halt-polling stop/deadlineSean Christopherson1-1/+1
Calculate the halt-polling "stop" time using "start" instead of redoing ktime_get(). In practice, the numbers involved are in the noise (e.g., in the happy case where hardware correctly predicts do_halt_poll and there are no interrupts, "start" is probably only a few cycles old) and either approach is perfectly ok. But it's more precise to count any extra latency toward the halt-polling time. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-17-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: stats: Add stat to detect if vcpu is currently blockingJing Zhang1-0/+4
Add a "blocking" stat that userspace can use to detect the case where a vCPU is not being run because of an vCPU/guest action, e.g. HLT or WFS on x86, WFI on arm64, etc... Current guest/host/halt stats don't show this well, e.g. if a guest halts for a long period of time then the vCPU could could appear pathologically blocked due to a host condition, when in reality the vCPU has been put into a not-runnable state by the guest. Originally-by: Cannon Matthews <cannonmatthews@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Jing Zhang <jingzhangos@google.com> [sean: renamed stat to "blocking", massaged changelog] Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-16-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt()Sean Christopherson1-16/+36
Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate non-halt wait/sleep/block conditions that should not be subjected to halt-polling. No functional change intended. Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-15-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt()Sean Christopherson1-11/+9
Rename kvm_vcpu_block() to kvm_vcpu_halt() in preparation for splitting the actual "block" sequences into a separate helper (to be named kvm_vcpu_block()). x86 will use the standalone block-only path to handle non-halt cases where the vCPU is not runnable. Rename block_ns to halt_ns to match the new function name. No functional change intended. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-14-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Drop obsolete kvm_arch_vcpu_block_finish()Sean Christopherson1-1/+0
Drop kvm_arch_vcpu_block_finish() now that all arch implementations are nops. No functional change intended. Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-10-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Don't block+unblock when halt-polling is successfulSean Christopherson1-3/+4
Invoke the arch hooks for block+unblock if and only if KVM actually attempts to block the vCPU. The only non-nop implementation is on x86, specifically SVM's AVIC, and there is no need to put the AVIC prior to halt-polling; KVM x86's kvm_vcpu_has_events() will scour the full vIRR to find pending IRQs regardless of whether the AVIC is loaded/"running". The primary motivation is to allow future cleanup to split out "block" from "halt", but this is also likely a small performance boost on x86 SVM when halt-polling is successful. Adjust the post-block path to update "cur" after unblocking, i.e. include AVIC load time in halt_wait_ns and halt_wait_hist, so that the behavior is consistent. Moving just the pre-block arch hook would result in only the AVIC put latency being included in the halt_wait stats. There is no obvious evidence that one way or the other is correct, so just ensure KVM is consistent. Note, x86 has two separate paths for handling APICv with respect to vCPU blocking. VMX uses hooks in x86's vcpu_block(), while SVM uses the arch hooks in kvm_vcpu_block(). Prior to this path, the two paths were more or less functionally identical. That is very much not the case after this patch, as the hooks used by VMX _must_ fire before halt-polling. x86's entire mess will be cleaned up in future patches. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-12-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Reconcile discrepancies in halt-polling statsSean Christopherson1-19/+16
Move the halt-polling "success" and histogram stats update into the dedicated helper to fix a discrepancy where the success/fail "time" stats consider polling successful so long as the wait is avoided, but the main "success" and histogram stats consider polling successful if and only if a wake event was detected by the halt-polling loop. Move halt_attempted_poll to the helper as well so that all the stats are updated in a single location. While it's a bit odd to update the stat well after the fact, practically speaking there's no meaningful advantage to updating before polling. Note, there is a functional change in addition to the success vs. fail change. The histogram updates previously called ktime_get() instead of using "cur". But that change is desirable as it means all the stats are now updated with the same polling time, and avoids the extra ktime_get(), which isn't expensive but isn't free either. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Refactor and document halt-polling stats update helperSean Christopherson1-7/+13
Add a comment to document that halt-polling is considered successful even if the polling loop itself didn't detect a wake event, i.e. if a wake event was detect in the final kvm_vcpu_check_block(). Invert the param to update helper so that the helper is a dumb function that is "told" whether or not polling was successful, as opposed to determining success based on blocking behavior. Opportunistically tweak the params to the update helper to reduce the line length for the call site so that it fits on a single line, and so that the prototype conforms to the more traditional kernel style. No functional change intended. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-7-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Update halt-polling stats if and only if halt-polling was attemptedSean Christopherson1-3/+5
Don't update halt-polling stats if halt-polling wasn't attempted. This is a nop as @poll_ns is guaranteed to be '0' (poll_end == start); in a future patch (to move the histogram stats into the helper), it will avoid to avoid a discrepancy in what is considered a "successful" halt-poll. No functional change intended. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-6-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Force PPC to define its own rcuwait objectSean Christopherson2-4/+7
Do not define/reference kvm_vcpu.wait if __KVM_HAVE_ARCH_WQP is true, and instead force the architecture (PPC) to define its own rcuwait object. Allowing common KVM to directly access vcpu->wait without a guard makes it all too easy to introduce potential bugs, e.g. kvm_vcpu_block(), kvm_vcpu_on_spin(), and async_pf_execute() all operate on vcpu->wait, not the result of kvm_arch_vcpu_get_wait(), and so may do the wrong thing for PPC. Due to PPC's shenanigans with respect to callbacks and waits (it switches to the virtual core's wait object at KVM_RUN!?!?), it's not clear whether or not this fixes any bugs. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-5-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPUSean Christopherson1-2/+3
Wrap s390's halt_poll_max_steal with READ_ONCE and snapshot the result of kvm_arch_no_poll() in kvm_vcpu_block() to avoid a mostly-theoretical, largely benign bug on s390 where the result of kvm_arch_no_poll() could change due to userspace modifying halt_poll_max_steal while the vCPU is blocking. The bug is largely benign as it will either cause KVM to skip updating halt-polling times (no_poll toggles false=>true) or to update halt-polling times with a slightly flawed block_ns. Note, READ_ONCE is unnecessary in the current code, add it in case the arch hook is ever inlined, and to provide a hint that userspace can change the param at will. Fixes: 8b905d28ee17 ("KVM: s390: provide kvm_arch_no_poll function") Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: Avoid atomic operations when kicking the running vCPUPaolo Bonzini1-1/+14
If we do have the vcpu mutex, as is the case if kvm_running_vcpu is set to the target vcpu of the kick, changes to vcpu->mode do not need atomic operations; cmpxchg is only needed _outside_ the mutex to ensure that the IN_GUEST_MODE->EXITING_GUEST_MODE change does not race with the vcpu thread going OUTSIDE_GUEST_MODE. Use this to optimize the case of a vCPU sending an interrupt to itself. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: x86/mmu: Propagate memslot const qualifierBen Gardon1-6/+6
In preparation for implementing in-place hugepage promotion, various functions will need to be called from zap_collapsible_spte_range, which has the const qualifier on its memslot argument. Propagate the const qualifier to the various functions which will be needed. This just serves to simplify the following patch. No functional change intended. Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20211115234603.2908381-11-bgardon@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-15 01:20:39 +0300