linux-kernel - [PATCH 42/43] KVM: VMX: Drop VMWRITEs to zero fields at vCPU RESET

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Message-Id: <20210424004645.3950558-43-seanjc@google.com>
Date:   Fri, 23 Apr 2021 17:46:44 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 42/43] KVM: VMX: Drop VMWRITEs to zero fields at vCPU RESET

Don't waste time writing zeros via VMWRITE during vCPU RESET, the VMCS
is zero allocated.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 29 -----------------------------
 1 file changed, 29 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 78d17adce7e6..74258ba4832a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4427,13 +4427,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 	}
 
 	if (kvm_vcpu_apicv_active(&vmx->vcpu)) {
-		vmcs_write64(EOI_EXIT_BITMAP0, 0);
-		vmcs_write64(EOI_EXIT_BITMAP1, 0);
-		vmcs_write64(EOI_EXIT_BITMAP2, 0);
-		vmcs_write64(EOI_EXIT_BITMAP3, 0);
-
-		vmcs_write16(GUEST_INTR_STATUS, 0);
-
 		vmcs_write16(POSTED_INTR_NV, POSTED_INTR_VECTOR);
 		vmcs_write64(POSTED_INTR_DESC_ADDR, __pa((&vmx->pi_desc)));
 	}
@@ -4444,23 +4437,9 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 		vmx->ple_window_dirty = true;
 	}
 
-	vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
-	vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
-	vmcs_write32(CR3_TARGET_COUNT, 0);           /* 22.2.1 */
-
-	vmcs_write16(HOST_FS_SELECTOR, 0);            /* 22.2.4 */
-	vmcs_write16(HOST_GS_SELECTOR, 0);            /* 22.2.4 */
 	vmx_set_constant_host_state(vmx);
-	vmcs_writel(HOST_FS_BASE, 0); /* 22.2.4 */
-	vmcs_writel(HOST_GS_BASE, 0); /* 22.2.4 */
 
-	if (cpu_has_vmx_vmfunc())
-		vmcs_write64(VM_FUNCTION_CONTROL, 0);
-
-	vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0);
-	vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0);
 	vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host.val));
-	vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0);
 	vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest.val));
 
 	if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT)
@@ -4493,7 +4472,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 		memset(&vmx->pt_desc, 0, sizeof(vmx->pt_desc));
 		/* Bit[6~0] are forced to 1, writes are ignored. */
 		vmx->pt_desc.guest.output_mask = 0x7F;
-		vmcs_write64(GUEST_IA32_RTIT_CTL, 0);
 	}
 
 	vmx_setup_uret_msrs(vmx);
@@ -4536,13 +4514,6 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	vmcs_write32(GUEST_LDTR_LIMIT, 0xffff);
 	vmcs_write32(GUEST_LDTR_AR_BYTES, 0x00082);
 
-	if (!init_event) {
-		vmcs_write32(GUEST_SYSENTER_CS, 0);
-		vmcs_writel(GUEST_SYSENTER_ESP, 0);
-		vmcs_writel(GUEST_SYSENTER_EIP, 0);
-		vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
-	}
-
 	vmcs_writel(GUEST_GDTR_BASE, 0);
 	vmcs_write32(GUEST_GDTR_LIMIT, 0xffff);
 
-- 
2.31.1.498.g6c1eba8ee3d-goog