From: Xiaoyao Li <xiaoyao.li@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/7] KVM: VMX: Restore host's MSR_IA32_RTIT_CTL when it's not zero
Date: Fri, 27 Aug 2021 15:02:43 +0800 [thread overview]
Message-ID: <20210827070249.924633-2-xiaoyao.li@intel.com> (raw)
In-Reply-To: <20210827070249.924633-1-xiaoyao.li@intel.com>
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>
---
Changes in v2:
- Refine comments
---
arch/x86/kvm/vmx/vmx.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fada1055f325..5535a86aea37 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,
--
2.27.0
next prev parent reply other threads:[~2021-08-27 7:03 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 7:02 [PATCH v2 0/7] KVM: VMX: PT (processor trace) optimization cleanup and fixes Xiaoyao Li
2021-08-27 7:02 ` Xiaoyao Li [this message]
2021-08-27 7:02 ` [PATCH v2 2/7] KVM: VMX: Use precomputed vmx->pt_desc.addr_range Xiaoyao Li
2021-08-27 7:02 ` [PATCH v2 3/7] KVM: VMX: Rename pt_desc.addr_range to pt_desc.nr_addr_range Xiaoyao Li
2021-10-18 12:41 ` Paolo Bonzini
2021-08-27 7:02 ` [PATCH v2 4/7] KVM: VMX: RTIT_CTL_BRANCH_EN has no dependency on other CPUID bit Xiaoyao Li
2021-08-27 7:02 ` [PATCH v2 5/7] KVM: VMX: Disallow PT MSRs accessing if PT is not exposed to guest Xiaoyao Li
2021-10-18 12:46 ` Paolo Bonzini
2021-08-27 7:02 ` [PATCH v2 6/7] KVM: VMX: Check Intel PT related CPUID leaves Xiaoyao Li
2021-09-09 21:41 ` Sean Christopherson
2021-09-10 1:59 ` Xiaoyao Li
2021-10-18 7:01 ` Xiaoyao Li
2021-10-18 12:47 ` Paolo Bonzini
2021-10-18 13:56 ` Xiaoyao Li
2021-10-18 17:26 ` Sean Christopherson
2021-10-19 1:46 ` Xiaoyao Li
2021-08-27 7:02 ` [PATCH v2 7/7] KVM: VMX: Only context switch some PT MSRs when they exist Xiaoyao Li
2021-10-18 13:08 ` Paolo Bonzini
2021-10-18 14:04 ` Xiaoyao Li
2021-10-18 15:20 ` Paolo Bonzini
2021-10-19 16:52 ` [PATCH v2 0/7] KVM: VMX: PT (processor trace) optimization cleanup and fixes Paolo Bonzini
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