- 15 Nov, 2019 19 commits
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Like Xu authored
Currently, a host perf_event is created for a vPMC functionality emulation. It’s unpredictable to determine if a disabled perf_event will be reused. If they are disabled and are not reused for a considerable period of time, those obsolete perf_events would increase host context switch overhead that could have been avoided. If the guest doesn't WRMSR any of the vPMC's MSRs during an entire vcpu sched time slice, and its independent enable bit of the vPMC isn't set, we can predict that the guest has finished the use of this vPMC, and then do request KVM_REQ_PMU in kvm_arch_sched_in and release those perf_events in the first call of kvm_pmu_handle_event() after the vcpu is scheduled in. This lazy mechanism delays the event release time to the beginning of the next scheduled time slice if vPMC's MSRs aren't changed during this time slice. If guest comes back to use this vPMC in next time slice, a new perf event would be re-created via perf_event_create_kernel_counter() as usual. Suggested-by:
Wei Wang <wei.w.wang@intel.com> Suggested-by:
Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:
Like Xu <like.xu@linux.intel.com> Signed-off-by:
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Like Xu authored
The perf_event_create_kernel_counter() in the pmc_reprogram_counter() is a heavyweight and high-frequency operation, especially when host disables the watchdog (maximum 21000000 ns) which leads to an unacceptable latency of the guest NMI handler. It limits the use of vPMUs in the guest. When a vPMC is fully enabled, the legacy reprogram_*_counter() would stop and release its existing perf_event (if any) every time EVEN in most cases almost the same requested perf_event will be created and configured again. For each vPMC, if the reuqested config ('u64 eventsel' for gp and 'u8 ctrl' for fixed) is the same as its current config AND a new sample period based on pmc->counter is accepted by host perf interface, the current event could be reused safely as a new created one does. Otherwise, do release the undesirable perf_event and reprogram a new one as usual. It's light-weight to call pmc_pause_counter (disable, read and reset event) and pmc_resume_counter (recalibrate period and re-enable event) as guest expects instead of release-and-create again on any condition. Compared to use the filterable event->attr or hw.config, a new 'u64 current_config' field is added to save the last original programed config for each vPMC. Based on this implementation, the number of calls to pmc_reprogram_counter is reduced by ~82.5% for a gp sampling event and ~99.9% for a fixed event. In the usage of multiplexing perf sampling mode, the average latency of the guest NMI handler is reduced from 104923 ns to 48393 ns (~2.16x speed up). If host disables watchdog, the minimum latecy of guest NMI handler could be speed up at ~3413x (from 20407603 to 5979 ns) and at ~786x in the average. Suggested-by:Kan Liang <kan.liang@linux.intel.com> Signed-off-by:
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Like Xu authored
Introduce a new callback msr_idx_to_pmc that returns a struct kvm_pmc*, and change kvm_pmu_is_valid_msr to return ".msr_idx_to_pmc(vcpu, msr) || .is_valid_msr(vcpu, msr)" and AMD just returns false from .is_valid_msr. Suggested-by:
kbuild test robot <lkp@intel.com> Signed-off-by:
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Like Xu authored
The leagcy pmu_ops->msr_idx_to_pmc is only called in kvm_pmu_rdpmc, so this function actually receives the contents of ECX before RDPMC, and translates it to a kvm_pmc. Let's clarify its semantic by renaming the existing msr_idx_to_pmc to rdpmc_ecx_to_pmc, and is_valid_msr_idx to is_valid_rdpmc_ecx; likewise for the wrapper kvm_pmu_is_valid_msr_idx. Suggested-by:
Jim Mattson <jmattson@google.com> Signed-off-by:
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Like Xu authored
Exporting perf_event_pause() as an external accessor for kernel users (such as KVM) who may do both disable perf_event and read count with just one time to hold perf_event_ctx_lock. Also the value could be reset optionally. Suggested-by:
Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Like Xu authored
Currently, perf_event_period() is used by user tools via ioctl. Based on naming convention, exporting perf_event_period() for kernel users (such as KVM) who may recalibrate the event period for their assigned counter according to their requirements. The perf_event_period() is an external accessor, just like the perf_event_{en,dis}able() and should thus use perf_event_ctx_lock(). Suggested-by: -
Liran Alon authored
When L1 don't use TPR-Shadow to run L2, L0 configures vmcs02 without TPR-Shadow and install intercepts on CR8 access (load and store). If L1 do not intercept L2 CR8 access, L0 intercepts on those accesses will emulate load/store on L1's LAPIC TPR. If in this case L2 lowers TPR such that there is now an injectable interrupt to L1, apic_update_ppr() will request a KVM_REQ_EVENT which will trigger a call to update_cr8_intercept() to update TPR-Threshold to highest pending IRR priority. However, this update to TPR-Threshold is done while active vmcs is vmcs02 instead of vmcs01. Thus, when later at some point L0 will emulate an exit from L2 to L1, L1 will still run with high TPR-Threshold. This will result in every VMEntry to L1 to immediately exit on TPR_BELOW_THRESHOLD and continue to do so infinitely until some condition will cause KVM_REQ_EVENT to be set. (Note that TPR_BELOW_THRESHOLD exit handler do not set KVM_REQ_EVENT until apic_update_ppr() will notice a new injectable interrupt for PPR) To fix this issue, change update_cr8_intercept() such that if L2 lowers L1's TPR in a way that requires to lower L1's TPR-Threshold, save update to TPR-Threshold and apply it to vmcs01 when L0 emulates an exit from L2 to L1. Reviewed-by:
Joao Martins <joao.m.martins@oracle.com> Signed-off-by:
Liran Alon <liran.alon@oracle.com> Signed-off-by:
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Liran Alon authored
No functional changes. Reviewed-by:
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Liran Alon authored
This check is unnecessary as x86 update_cr8_intercept() which calls this VMX/SVM specific callback already performs this check. Reviewed-by:
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Miaohe Lin authored
There are some duplicate code in kvm_pv_send_ipi when deal with ipi bitmap. Add helper func to remove it, and eliminate odd out label, get rid of unnecessary kvm_lapic_irq field init and so on. Signed-off-by:
Miaohe Lin <linmiaohe@huawei.com> Signed-off-by:
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Miaohe Lin authored
When SYSCALL/SYSENTER ability check failed, cs and ss is inited but remain not used. Delay initializing cs and ss until SYSCALL/SYSENTER ability check passed. Signed-off-by:
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Miaohe Lin authored
The out_err label and var ret is unnecessary, clean them up. Signed-off-by:
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Liran Alon authored
Intel SDM section 25.2 OTHER CAUSES OF VM EXITS specifies the following on INIT signals: "Such exits do not modify register state or clear pending events as they would outside of VMX operation." When commit 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") was applied, I interepted above Intel SDM statement such that INIT_SIGNAL exit don’t consume the LAPIC INIT pending event. However, when Nadav Amit run matching kvm-unit-test on a bare-metal machine, it turned out my interpetation was wrong. i.e. INIT_SIGNAL exit does consume the LAPIC INIT pending event. (See: https://www.spinics.net/lists/kvm/msg196757.html) Therefore, fix KVM code to behave as observed on bare-metal. Fixes: 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") Reported-by:
Nadav Amit <nadav.amit@gmail.com> Reviewed-by:
Mihai Carabas <mihai.carabas@oracle.com> Reviewed-by:
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Liran Alon authored
Commit 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") fixed KVM to also latch pending LAPIC INIT event when vCPU is in VMX operation. However, current API of KVM_SET_MP_STATE allows userspace to put vCPU into KVM_MP_STATE_SIPI_RECEIVED or KVM_MP_STATE_INIT_RECEIVED even when vCPU is in VMX operation. Fix this by introducing a util method to check if vCPU state latch INIT signals and use it in KVM_SET_MP_STATE handler. Fixes: 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") Reported-by:
Sean Christopherson <sean.j.christopherson@intel.com> Reviewed-by:
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Liran Alon authored
Commit 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") fixed KVM to also latch pending LAPIC INIT event when vCPU is in VMX operation. However, current API of KVM_SET_VCPU_EVENTS defines this field as part of SMM state and only set pending LAPIC INIT event if vCPU is specified to be in SMM mode (events->smi.smm is set). Change KVM_SET_VCPU_EVENTS handler to set pending LAPIC INIT event by latched_init field regardless of if vCPU is in SMM mode or not. Fixes: 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states") Reviewed-by:
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Andrea Arcangeli authored
It's enough to check the value and issue the direct call. After this commit is applied, here the most common retpolines executed under a high resolution timer workload in the guest on a VMX host: [..] @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 267 @[]: 2256 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 __kvm_wait_lapic_expire+284 vmx_vcpu_run.part.97+1091 vcpu_enter_guest+377 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 2390 @[]: 33410 @total: 315707 Note the highest hit above is __delay so probably not worth optimizing even if it would be more frequent than 2k hits per sec. Signed-off-by:Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:
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Andrea Arcangeli authored
It's enough to check the exit value and issue a direct call to avoid the retpoline for all the common vmexit reasons. After this commit is applied, here the most common retpolines executed under a high resolution timer workload in the guest on a SVM host: [..] @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get_update_offsets_now+70 hrtimer_interrupt+131 smp_apic_timer_interrupt+106 apic_timer_interrupt+15 start_sw_timer+359 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 1940 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_r12+33 force_qs_rnp+217 rcu_gp_kthread+1270 kthread+268 ret_from_fork+34 ]: 4644 @[]: 25095 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 lapic_next_event+28 clockevents_program_event+148 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41474 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 clockevents_program_event+148 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41474 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 clockevents_program_event+84 hrtimer_start_range_ns+528 start_sw_timer+356 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 41887 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 lapic_next_event+28 clockevents_program_event+148 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42723 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 clockevents_program_event+148 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42766 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 clockevents_program_event+84 hrtimer_try_to_cancel+168 hrtimer_cancel+21 kvm_set_lapic_tscdeadline_msr+43 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 42848 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 ktime_get+58 start_sw_timer+279 restart_apic_timer+85 kvm_set_msr_common+1497 msr_interception+142 vcpu_enter_guest+684 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 499845 @total: 1780243 SVM has no TSC based programmable preemption timer so it is invoking ktime_get() frequently. Signed-off-by: -
Andrea Arcangeli authored
It's enough to check the exit value and issue a direct call to avoid the retpoline for all the common vmexit reasons. Of course CONFIG_RETPOLINE already forbids gcc to use indirect jumps while compiling all switch() statements, however switch() would still allow the compiler to bisect the case value. It's more efficient to prioritize the most frequent vmexits instead. The halt may be slow paths from the point of the guest, but not necessarily so from the point of the host if the host runs at full CPU capacity and no host CPU is ever left idle. Signed-off-by:
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Andrea Arcangeli authored
Eliminate wasteful call/ret non RETPOLINE case and unnecessary fentry dynamic tracing hooking points. Signed-off-by:
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- 11 Nov, 2019 1 commit
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Miaohe Lin authored
The odd out jump label is really not needed. Get rid of it by return true directly while r < 0 as suggested by Paolo. This further lead to var changed being unused. Remove it too. Signed-off-by:
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- 02 Nov, 2019 1 commit
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Marcelo Tosatti authored
Commit 0bc48bea ("KVM: x86: update master clock before computing kvmclock_offset") switches the order of operations to avoid the conversion TSC (without frequency correction) -> system_timestamp (with frequency correction), which might cause a time jump. However, it leaves any other masterclock update unsafe, which includes, at the moment: * HV_X64_MSR_REFERENCE_TSC MSR write. * TSC writes. * Host suspend/resume. Avoid the time jump issue by using frequency uncorrected CLOCK_MONOTONIC_RAW clock. Its the guests time keeping software responsability to track and correct a reference clock such as UTC. This fixes forward time jump (which can result in failure to bring up a vCPU) during vCPU hotplug: Oct 11 14:48:33 storage kernel: CPU2 has been hot-added Oct 11 14:48:34 storage kernel: CPU3 has been hot-added Oct 11 14:49:22 storage kernel: smpboot: Booting Node 0 Processor 2 APIC 0x2 <-- time jump of almost 1 minute Oct 11 14:49:22 storage kernel: smpboot: do_boot_cpu failed(-1) to wakeup CPU#2 Oct 11 14:49:23 storage kernel: smpboot: Booting Node 0 Processor 3 APIC 0x3 Oct 11 14:49:23 storage kernel: kvm-clock: cpu 3, msr 0:7ff640c1, secondary cpu clock Which happens because: /* * Wait 10s total for a response from AP */ boot_error = -1; timeout = jiffies + 10*HZ; while (time_before(jiffies, timeout)) { ... } Analyzed-by:
Igor Mammedov <imammedo@redhat.com> Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:
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- 31 Oct, 2019 1 commit
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Paolo Bonzini authored
Merge tag 'kvm-ppc-next-5.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD KVM PPC update for 5.5 * Add capability to tell userspace whether we can single-step the guest. * Improve the allocation of XIVE virtual processor IDs, to reduce the risk of running out of IDs when running many VMs on POWER9. * Rewrite interrupt synthesis code to deliver interrupts in virtual mode when appropriate. * Minor cleanups and improvements.
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- 25 Oct, 2019 1 commit
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Yi Wang authored
We get two warning when build kernel with W=1: arch/x86/kernel/kvm.c:872:6: warning: no previous prototype for ‘arch_haltpoll_enable’ [-Wmissing-prototypes] arch/x86/kernel/kvm.c:885:6: warning: no previous prototype for ‘arch_haltpoll_disable’ [-Wmissing-prototypes] Including the missing head file can fix this. Signed-off-by:
Yi Wang <wang.yi59@zte.com.cn> Signed-off-by:
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- 22 Oct, 2019 17 commits
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Sean Christopherson authored
Add a new helper, kvm_put_kvm_no_destroy(), to handle putting a borrowed reference[*] to the VM when installing a new file descriptor fails. KVM expects the refcount to remain valid in this case, as the in-progress ioctl() has an explicit reference to the VM. The primary motiviation for the helper is to document that the 'kvm' pointer is still valid after putting the borrowed reference, e.g. to document that doing mutex(&kvm->lock) immediately after putting a ref to kvm isn't broken. [*] When exposing a new object to userspace via a file descriptor, e.g. a new vcpu, KVM grabs a reference to itself (the VM) prior to making the object visible to userspace to avoid prematurely freeing the VM in the scenario where userspace immediately closes file descriptor. Signed-off-by: -
Aaron Lewis authored
Ensure that IA32_XSS appears in KVM_GET_MSR_INDEX_LIST if it can be set to a non-zero value. Reviewed-by:
Aaron Lewis <aaronlewis@google.com> Change-Id: Ia2d644f69e2d6d8c27d7e0a7a45c2bf9c42bf5ff Signed-off-by:
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Aaron Lewis authored
AMD CPUs now support XSAVES in a limited fashion (they require IA32_XSS to be zero). AMD has no equivalent of Intel's "Enable XSAVES/XRSTORS" VM-execution control. Instead, XSAVES is always available to the guest when supported on the host. Reviewed-by:
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Aaron Lewis authored
Hoist support for RDMSR/WRMSR of IA32_XSS from vmx into common code so that it can be used for svm as well. Right now, kvm only allows the guest IA32_XSS to be zero, so the guest's usage of XSAVES will be exactly the same as XSAVEC. Reviewed-by:
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Aaron Lewis authored
Hoist the vendor-specific code related to loading the hardware IA32_XSS MSR with guest/host values on VM-entry/VM-exit to common x86 code. Reviewed-by:
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Aaron Lewis authored
When the guest can execute the XSAVES/XRSTORS instructions, use wrmsr to set the hardware IA32_XSS MSR to guest/host values on VM-entry/VM-exit, rather than the MSR-load areas. By using the same approach as AMD, we will be able to use a common implementation for both (in the next patch). Reviewed-by:
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Aaron Lewis authored
When the guest can execute the XSAVES/XRSTORS instructions, set the hardware IA32_XSS MSR to guest/host values on VM-entry/VM-exit. Note that vcpu->arch.ia32_xss is currently guaranteed to be 0 on AMD, since there is no way to change it. Suggested-by:
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Aaron Lewis authored
The kvm_vcpu variable, guest_xcr0_loaded, is a waste of an 'int' and a conditional branch. VMX and SVM are the only users, and both unconditionally pair kvm_load_guest_xcr0() with kvm_put_guest_xcr0() making this check unnecessary. Without this variable, the predicates in kvm_load_guest_xcr0 and kvm_put_guest_xcr0 should match. Suggested-by:
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Aaron Lewis authored
Volume 4 of the SDM says that IA32_XSS is supported if CPUID(EAX=0DH,ECX=1):EAX.XSS[bit 3] is set, so only the X86_FEATURE_XSAVES check is necessary (X86_FEATURE_XSAVES is the Linux name for CPUID(EAX=0DH,ECX=1):EAX.XSS[bit 3]). Fixes: 4d763b16 ("KVM: VMX: check CPUID before allowing read/write of IA32_XSS") Reviewed-by:
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Aaron Lewis authored
Cache whether XSAVES is enabled in the guest by adding xsaves_enabled to vcpu->arch. Reviewed-by:
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Xiaoyao Li authored
Rename {vmx,nested_vmx}_vcpu_setup() to match what they really do. Signed-off-by:Xiaoyao Li <xiaoyao.li@intel.com> Signed-off-by:
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Xiaoyao Li authored
Move the initialization of vmx->guest_msrs[] from vmx_vcpu_setup() to vmx_create_vcpu(), and put it right after its allocation. This also is the preperation for next patch. Signed-off-by:
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Xiaoyao Li authored
... It can be removed here because the same code is called later in vmx_vcpu_reset() as the flow: kvm_arch_vcpu_setup() -> kvm_vcpu_reset() -> vmx_vcpu_reset() Signed-off-by:
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Xiaoyao Li authored
Move the code that writes vmx->vpid to vmcs from vmx_vcpu_reset() to vmx_vcpu_setup(), because vmx->vpid is allocated when creating vcpu and never changed. So we don't need to update the vmcs.vpid when resetting vcpu. Signed-off-by:
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Like Xu authored
Replace the explicit declaration of "u64 reprogram_pmi" with the generic macro DECLARE_BITMAP for all possible appropriate number of bits. Suggested-by:
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Miaohe Lin authored
If we reach here with r = 0, we will reassign r = 0 unnecesarry, then do the label set_irqchip_out work. If we reach here with r != 0, then we will do the label work directly. So this if statement and r = 0 assignment is redundant. Signed-off-by:
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Suthikulpanit, Suravee authored
Generally, APICv for all vcpus in the VM are enable/disable in the same manner. So, get_enable_apicv() should represent APICv status of the VM instead of each VCPU. Modify kvm_x86_ops.get_enable_apicv() to take struct kvm as parameter instead of struct kvm_vcpu. Reviewed-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Signed-off-by:
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