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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: 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 37/43] KVM: nVMX: Remove obsolete MSR bitmap refresh at nested transitions
Date: Fri, 23 Apr 2021 17:46:39 -0700	[thread overview]
Message-ID: <20210424004645.3950558-38-seanjc@google.com> (raw)
In-Reply-To: <20210424004645.3950558-1-seanjc@google.com>

Drop unnecessary MSR bitmap updates during nested transitions, as L1's
APIC_BASE MSR is not modified by the standard VM-Enter/VM-Exit flows,
and L2's MSR bitmap is managed separately.  In the unlikely event that L1
is pathological and loads APIC_BASE via the VM-Exit load list, KVM will
handle updating the bitmap in its normal WRMSR flows.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/nested.c | 6 ------
 arch/x86/kvm/vmx/vmx.c    | 2 +-
 arch/x86/kvm/vmx/vmx.h    | 1 -
 3 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f811bb7f2dc3..9dcdf158a405 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4283,9 +4283,6 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
 	kvm_set_dr(vcpu, 7, 0x400);
 	vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
 
-	if (cpu_has_vmx_msr_bitmap())
-		vmx_update_msr_bitmap(vcpu);
-
 	if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr,
 				vmcs12->vm_exit_msr_load_count))
 		nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
@@ -4364,9 +4361,6 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu)
 
 	kvm_mmu_reset_context(vcpu);
 
-	if (cpu_has_vmx_msr_bitmap())
-		vmx_update_msr_bitmap(vcpu);
-
 	/*
 	 * This nasty bit of open coding is a compromise between blindly
 	 * loading L1's MSRs using the exit load lists (incorrect emulation
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index acfb87f30979..45a013631f63 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3984,7 +3984,7 @@ static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu, u8 mode)
 	}
 }
 
-void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu)
+static void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u8 mode = vmx_msr_bitmap_mode(vcpu);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 1283ad0e592d..e46df3253a21 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -380,7 +380,6 @@ void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
 u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
 
 void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu);
-void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu);
 bool vmx_nmi_blocked(struct kvm_vcpu *vcpu);
 bool vmx_interrupt_blocked(struct kvm_vcpu *vcpu);
 bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu);
-- 
2.31.1.498.g6c1eba8ee3d-goog


  parent reply	other threads:[~2021-04-24  0:55 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-24  0:46 [PATCH 00/43] KVM: x86: vCPU RESET/INIT fixes and consolidation Sean Christopherson
2021-04-24  0:46 ` [PATCH 01/43] KVM: nVMX: Set LDTR to its architecturally defined value on nested VM-Exit Sean Christopherson
2021-05-19  5:30   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 02/43] KVM: VMX: Set EDX at INIT with CPUID.0x1, Family-Model-Stepping Sean Christopherson
2021-05-19  5:59   ` Reiji Watanabe
2021-05-19 18:47     ` Sean Christopherson
2021-05-21  7:07       ` Reiji Watanabe
2021-05-21 15:28         ` Sean Christopherson
2021-05-24  4:29           ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 03/43] KVM: SVM: Require exact CPUID.0x1 match when stuffing EDX at INIT Sean Christopherson
2021-05-19  5:30   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 04/43] KVM: SVM: Fall back to KVM's hardcoded value for EDX at RESET/INIT Sean Christopherson
2021-05-19  5:41   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 05/43] KVM: x86: Split out CR0/CR4 MMU role change detectors to separate helpers Sean Christopherson
2021-05-19  5:31   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 06/43] KVM: x86: Properly reset MMU context at vCPU RESET/INIT Sean Christopherson
2021-05-17 16:57   ` Reiji Watanabe
2021-05-18 20:23     ` Sean Christopherson
2021-05-18 22:42       ` Reiji Watanabe
2021-05-19 17:16         ` Sean Christopherson
2021-05-24  4:57           ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 07/43] KVM: VMX: Remove explicit MMU reset in enter_rmode() Sean Christopherson
2021-04-24  0:46 ` [PATCH 08/43] KVM: SVM: Drop explicit MMU reset at RESET/INIT Sean Christopherson
2021-05-19  5:32   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 09/43] KVM: SVM: Drop a redundant init_vmcb() from svm_create_vcpu() Sean Christopherson
2021-05-19  5:32   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 10/43] KVM: VMX: Move init_vmcs() invocation to vmx_vcpu_reset() Sean Christopherson
2021-05-19  5:33   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 11/43] KVM: x86: WARN if the APIC map is dirty without an in-kernel local APIC Sean Christopherson
2021-04-24  0:46 ` [PATCH 12/43] KVM: x86: Remove defunct BSP "update" in local APIC reset Sean Christopherson
2021-05-26  6:54   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 13/43] KVM: x86: Migrate the PIT only if vcpu0 is migrated, not any BSP Sean Christopherson
2021-04-24  0:46 ` [PATCH 14/43] KVM: x86: Don't force set BSP bit when local APIC is managed by userspace Sean Christopherson
2021-05-26  6:55   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 15/43] KVM: x86: Set BSP bit in reset BSP vCPU's APIC base by default Sean Christopherson
2021-05-26  6:55   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 16/43] KVM: VMX: Stuff vcpu->arch.apic_base directly at vCPU RESET Sean Christopherson
2021-05-26  6:55   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 17/43] KVM: x86: Open code necessary bits of kvm_lapic_set_base() " Sean Christopherson
2021-05-26  7:04   ` Reiji Watanabe
2021-05-26 15:15     ` Sean Christopherson
2021-04-24  0:46 ` [PATCH 18/43] KVM: x86: Consolidate APIC base RESET initialization code Sean Christopherson
2021-05-26  7:04   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 19/43] KVM: x86: Move EDX initialization at vCPU RESET to common code Sean Christopherson
2021-05-19  5:45   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 20/43] KVM: SVM: Don't bother writing vmcb->save.rip at vCPU RESET/INIT Sean Christopherson
2021-05-19  5:34   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 21/43] KVM: VMX: Invert handling of CR0.WP for EPT without unrestricted guest Sean Christopherson
2021-04-24  0:46 ` [PATCH 22/43] KVM: VMX: Remove direct write to vcpu->arch.cr0 during vCPU RESET/INIT Sean Christopherson
2021-05-19  5:34   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 23/43] KVM: VMX: Fold ept_update_paging_mode_cr0() back into vmx_set_cr0() Sean Christopherson
2021-04-24  0:46 ` [PATCH 24/43] KVM: nVMX: Do not clear CR3 load/store exiting bits if L1 wants 'em Sean Christopherson
2021-04-24  0:46 ` [PATCH 25/43] KVM: VMX: Pull GUEST_CR3 from the VMCS iff CR3 load exiting is disabled Sean Christopherson
2021-04-24  0:46 ` [PATCH 26/43] KVM: VMX: Process CR0.PG side effects after setting CR0 assets Sean Christopherson
2021-04-24  0:46 ` [PATCH 27/43] KVM: VMX: Skip emulation required checks during pmode/rmode transitions Sean Christopherson
2021-04-24  0:46 ` [PATCH 28/43] KVM: nVMX: Don't evaluate "emulation required" on VM-Exit Sean Christopherson
2021-04-24  0:46 ` [PATCH 29/43] KVM: SVM: Tweak order of cr0/cr4/efer writes at RESET/INIT Sean Christopherson
2021-05-19 18:16   ` Reiji Watanabe
2021-05-19 19:58     ` Sean Christopherson
2021-05-23 23:04       ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 30/43] KVM: SVM: Drop redundant writes to vmcb->save.cr4 " Sean Christopherson
2021-05-19  5:35   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 31/43] KVM: SVM: Stuff save->dr6 at during VMSA sync, not " Sean Christopherson
2021-04-24  0:46 ` [PATCH 32/43] KVM: VMX: Skip pointless MSR bitmap update when setting EFER Sean Christopherson
2021-04-24  0:46 ` [PATCH 33/43] KVM: VMX: Refresh list of user return MSRs after setting guest CPUID Sean Christopherson
2021-05-19  5:35   ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 34/43] KVM: VMX: Don't _explicitly_ reconfigure user return MSRs on vCPU INIT Sean Christopherson
2021-04-24  0:46 ` [PATCH 35/43] KVM: x86: Move setting of sregs during vCPU RESET/INIT to common x86 Sean Christopherson
2021-05-17 23:50   ` Reiji Watanabe
2021-05-18 21:45     ` Sean Christopherson
2021-05-21  5:19       ` Reiji Watanabe
2021-04-24  0:46 ` [PATCH 36/43] KVM: VMX: Remove obsolete MSR bitmap refresh at vCPU RESET/INIT Sean Christopherson
2021-04-24  0:46 ` Sean Christopherson [this message]
2021-04-24  0:46 ` [PATCH 38/43] KVM: VMX: Don't redo x2APIC MSR bitmaps when userspace filter is changed Sean Christopherson
2021-04-24  0:46 ` [PATCH 39/43] KVM: VMX: Remove unnecessary initialization of msr_bitmap_mode Sean Christopherson
2021-04-24  0:46 ` [PATCH 40/43] KVM: VMX: Smush x2APIC MSR bitmap adjustments into single function Sean Christopherson
2021-04-24  0:46 ` [PATCH 41/43] KVM: VMX: Remove redundant write to set vCPU as active at RESET/INIT Sean Christopherson
2021-04-24  0:46 ` [PATCH 42/43] KVM: VMX: Drop VMWRITEs to zero fields at vCPU RESET Sean Christopherson
2021-05-24 21:15   ` Paolo Bonzini
2021-05-24 22:21     ` Jim Mattson
2021-05-24 22:28     ` Sean Christopherson
2021-05-24 22:48       ` Jim Mattson
2021-05-25  1:02         ` Sean Christopherson
2021-04-24  0:46 ` [PATCH 43/43] KVM: x86: Drop pointless @reset_roots from kvm_init_mmu() Sean Christopherson
2021-05-27 19:11   ` Sean Christopherson
2021-05-27 19:25     ` Sean Christopherson
2021-06-10 16:54 ` [PATCH 00/43] KVM: x86: vCPU RESET/INIT fixes and consolidation Paolo Bonzini
2021-06-10 19:22   ` Sean Christopherson

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