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| author | Xiaoyao Li <xiaoyao.li@intel.com> | 2021-08-27 10:02:43 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-10-22 12:19:26 +0300 |
| commit | 2e6e0d683b77b1e08e5e03146ca3b8e033492666 (patch) | |
| tree | 70f543e2d0974c14b4680dfcb4196fbd764df780 /arch/x86/kvm | |
| parent | 2839180ce5bb27ad5e1f092fdafede284a925e5c (diff) | |
| download | linux-2e6e0d683b77b1e08e5e03146ca3b8e033492666.tar.xz | |
KVM: VMX: Restore host's MSR_IA32_RTIT_CTL when it's not zero
A minor optimization to WRMSR MSR_IA32_RTIT_CTL when necessary.
Opportunistically refine the comment to call out that KVM requires
VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20210827070249.924633-2-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1c8b2b6e7ed9..9a8cd7f8481e 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1074,8 +1074,12 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) pt_load_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range); } - /* Reload host state (IA32_RTIT_CTL will be cleared on VM exit). */ - wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); + /* + * KVM requires VM_EXIT_CLEAR_IA32_RTIT_CTL to expose PT to the guest, + * i.e. RTIT_CTL is always cleared on VM-Exit. Restore it if necessary. + */ + if (vmx->pt_desc.host.ctl) + wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); } void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel, |