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From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	vkuznets@redhat.com
Subject: [PATCH 38/43] KVM: VMX: Explicitly initialize controls shadow at VMCS allocation
Date: Thu, 13 Jun 2019 19:03:24 +0200
Message-ID: <1560445409-17363-39-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1560445409-17363-1-git-send-email-pbonzini@redhat.com>

From: Sean Christopherson <sean.j.christopherson@intel.com>

Or: Don't re-initialize vmcs02's controls on every nested VM-Entry.

VMWRITEs to the major VMCS controls are deceptively expensive.  Intel
CPUs with VMCS caching (Westmere and later) also optimize away
consistency checks on VM-Entry, i.e. skip consistency checks if the
relevant fields have not changed since the last successful VM-Entry (of
the cached VMCS).  Because uops are a precious commodity, uCode's dirty
VMCS field tracking isn't as precise as software would prefer.  Notably,
writing any of the major VMCS fields effectively marks the entire VMCS
dirty, i.e. causes the next VM-Entry to perform all consistency checks,
which consumes several hundred cycles.

Zero out the controls' shadow copies during VMCS allocation and use the
optimized setter when "initializing" controls.  While this technically
affects both non-nested and nested virtualization, nested virtualization
is the primary beneficiary as avoid VMWRITEs when prepare vmcs02 allows
hardware to optimizie away consistency checks.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/nested.c | 10 +++++-----
 arch/x86/kvm/vmx/vmx.c    | 12 +++++++-----
 arch/x86/kvm/vmx/vmx.h    |  5 -----
 3 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 47adafa42fbf..32bcf777576c 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2024,7 +2024,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	} else {
 		exec_control &= ~PIN_BASED_POSTED_INTR;
 	}
-	pin_controls_init(vmx, exec_control);
+	pin_controls_set(vmx, exec_control);
 
 	/*
 	 * EXEC CONTROLS
@@ -2049,7 +2049,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	 */
 	exec_control &= ~CPU_BASED_USE_IO_BITMAPS;
 	exec_control |= CPU_BASED_UNCOND_IO_EXITING;
-	exec_controls_init(vmx, exec_control);
+	exec_controls_set(vmx, exec_control);
 
 	/*
 	 * SECONDARY EXEC CONTROLS
@@ -2079,7 +2079,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 			vmcs_write16(GUEST_INTR_STATUS,
 				vmcs12->guest_intr_status);
 
-		secondary_exec_controls_init(vmx, exec_control);
+		secondary_exec_controls_set(vmx, exec_control);
 	}
 
 	/*
@@ -2098,7 +2098,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 		if (guest_efer != host_efer)
 			exec_control |= VM_ENTRY_LOAD_IA32_EFER;
 	}
-	vm_entry_controls_init(vmx, exec_control);
+	vm_entry_controls_set(vmx, exec_control);
 
 	/*
 	 * EXIT CONTROLS
@@ -2110,7 +2110,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	exec_control = vmx_vmexit_ctrl();
 	if (cpu_has_load_ia32_efer() && guest_efer != host_efer)
 		exec_control |= VM_EXIT_LOAD_IA32_EFER;
-	vm_exit_controls_init(vmx, exec_control);
+	vm_exit_controls_set(vmx, exec_control);
 
 	/*
 	 * Interrupt/Exception Fields
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1104f52d281c..6afb2bc3d0ab 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2485,6 +2485,8 @@ int alloc_loaded_vmcs(struct loaded_vmcs *loaded_vmcs)
 	}
 
 	memset(&loaded_vmcs->host_state, 0, sizeof(struct vmcs_host_state));
+	memset(&loaded_vmcs->controls_shadow, 0,
+		sizeof(struct vmcs_controls_shadow));
 
 	return 0;
 
@@ -4040,14 +4042,14 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
 	vmcs_write64(VMCS_LINK_POINTER, -1ull); /* 22.3.1.5 */
 
 	/* Control */
-	pin_controls_init(vmx, vmx_pin_based_exec_ctrl(vmx));
+	pin_controls_set(vmx, vmx_pin_based_exec_ctrl(vmx));
 	vmx->hv_deadline_tsc = -1;
 
-	exec_controls_init(vmx, vmx_exec_control(vmx));
+	exec_controls_set(vmx, vmx_exec_control(vmx));
 
 	if (cpu_has_secondary_exec_ctrls()) {
 		vmx_compute_secondary_exec_control(vmx);
-		secondary_exec_controls_init(vmx, vmx->secondary_exec_control);
+		secondary_exec_controls_set(vmx, vmx->secondary_exec_control);
 	}
 
 	if (kvm_vcpu_apicv_active(&vmx->vcpu)) {
@@ -4105,10 +4107,10 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
 		++vmx->nmsrs;
 	}
 
-	vm_exit_controls_init(vmx, vmx_vmexit_ctrl());
+	vm_exit_controls_set(vmx, vmx_vmexit_ctrl());
 
 	/* 22.2.1, 20.8.1 */
-	vm_entry_controls_init(vmx, vmx_vmentry_ctrl());
+	vm_entry_controls_set(vmx, vmx_vmentry_ctrl());
 
 	vmx->vcpu.arch.cr0_guest_owned_bits = X86_CR0_TS;
 	vmcs_writel(CR0_GUEST_HOST_MASK, ~X86_CR0_TS);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 6f26f3c10805..dddd36cf7c62 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -388,11 +388,6 @@ static inline u8 vmx_get_rvi(void)
 }
 
 #define BUILD_CONTROLS_SHADOW(lname, uname)				    \
-static inline void lname##_controls_init(struct vcpu_vmx *vmx, u32 val)	    \
-{									    \
-	vmcs_write32(uname, val);					    \
-	vmx->loaded_vmcs->controls_shadow.lname = val;			    \
-}									    \
 static inline void lname##_controls_set(struct vcpu_vmx *vmx, u32 val)	    \
 {									    \
 	if (vmx->loaded_vmcs->controls_shadow.lname != val) {		    \
-- 
1.8.3.1



  parent reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13 17:02 [PATCH 00/43] VMX optimizations Paolo Bonzini
2019-06-13 17:02 ` [PATCH 01/43] KVM: VMX: Fix handling of #MC that occurs during VM-Entry Paolo Bonzini
2019-06-13 17:24   ` Jim Mattson
2019-06-13 17:02 ` [PATCH 02/43] kvm: nVMX: small cleanup in handle_exception Paolo Bonzini
2019-06-13 17:02 ` [PATCH 03/43] KVM: VMX: Read cached VM-Exit reason to detect external interrupt Paolo Bonzini
2019-06-13 17:02 ` [PATCH 04/43] KVM: VMX: Store the host kernel's IDT base in a global variable Paolo Bonzini
2019-06-13 17:02 ` [PATCH 05/43] KVM: x86: Move kvm_{before,after}_interrupt() calls to vendor code Paolo Bonzini
2019-06-13 17:02 ` [PATCH 06/43] KVM: VMX: Handle NMIs, #MCs and async #PFs in common irqs-disabled fn Paolo Bonzini
2019-06-13 17:02 ` [PATCH 07/43] KVM: nVMX: Intercept VMWRITEs to read-only shadow VMCS fields Paolo Bonzini
2019-06-13 17:02 ` [PATCH 08/43] KVM: nVMX: Intercept VMWRITEs to GUEST_{CS,SS}_AR_BYTES Paolo Bonzini
2019-06-13 17:02 ` [PATCH 09/43] KVM: nVMX: Track vmcs12 offsets for shadowed VMCS fields Paolo Bonzini
2019-06-13 17:02 ` [PATCH 10/43] KVM: nVMX: Lift sync_vmcs12() out of prepare_vmcs12() Paolo Bonzini
2019-06-13 17:02 ` [PATCH 11/43] KVM: nVMX: Use descriptive names for VMCS sync functions and flags Paolo Bonzini
2019-06-13 17:02 ` [PATCH 12/43] KVM: nVMX: Add helpers to identify shadowed VMCS fields Paolo Bonzini
2019-06-14 16:10   ` Sean Christopherson
2019-06-13 17:02 ` [PATCH 13/43] KVM: nVMX: Sync rarely accessed guest fields only when needed Paolo Bonzini
2019-06-13 17:03 ` [PATCH 14/43] KVM: nVMX: Rename prepare_vmcs02_*_full to prepare_vmcs02_*_rare Paolo Bonzini
2019-06-13 17:03 ` [PATCH 15/43] KVM: VMX: Always signal #GP on WRMSR to MSR_IA32_CR_PAT with bad value Paolo Bonzini
2019-06-13 17:03 ` [PATCH 16/43] KVM: nVMX: Always sync GUEST_BNDCFGS when it comes from vmcs01 Paolo Bonzini
     [not found]   ` <20190615221602.93C5721851@mail.kernel.org>
2019-06-15 22:40     ` Liran Alon
2019-06-13 17:03 ` [PATCH 17/43] KVM: nVMX: Write ENCLS-exiting bitmap once per vmcs02 Paolo Bonzini
2019-06-13 17:03 ` [PATCH 18/43] KVM: nVMX: Don't rewrite GUEST_PML_INDEX during nested VM-Entry Paolo Bonzini
2019-06-13 17:03 ` [PATCH 19/43] KVM: VMX: simplify vmx_prepare_switch_to_{guest,host} Paolo Bonzini
2019-06-13 17:03 ` [PATCH 20/43] KVM: nVMX: Don't "put" vCPU or host state when switching VMCS Paolo Bonzini
2019-06-13 17:03 ` [PATCH 21/43] KVM: nVMX: Don't reread VMCS-agnostic " Paolo Bonzini
2019-06-14 16:25   ` Sean Christopherson
2019-06-13 17:03 ` [PATCH 22/43] KVM: nVMX: Don't dump VMCS if virtual APIC page can't be mapped Paolo Bonzini
2019-06-17 19:17   ` Radim Krčmář
2019-06-17 20:07     ` Sean Christopherson
2019-06-18  9:43       ` Paolo Bonzini
2019-06-13 17:03 ` [PATCH 23/43] KVM: nVMX: Don't speculatively write virtual-APIC page address Paolo Bonzini
2019-06-13 17:03 ` [PATCH 24/43] KVM: nVMX: Don't speculatively write APIC-access " Paolo Bonzini
2019-06-13 17:03 ` [PATCH 25/43] KVM: nVMX: Update vmcs12 for MSR_IA32_CR_PAT when it's written Paolo Bonzini
2019-06-13 17:03 ` [PATCH 26/43] KVM: nVMX: Update vmcs12 for SYSENTER MSRs when they're written Paolo Bonzini
2019-06-13 17:03 ` [PATCH 27/43] KVM: nVMX: Update vmcs12 for MSR_IA32_DEBUGCTLMSR when it's written Paolo Bonzini
2019-06-13 17:03 ` [PATCH 28/43] KVM: nVMX: Don't update GUEST_BNDCFGS if it's clean in HV eVMCS Paolo Bonzini
2019-06-13 17:03 ` [PATCH 29/43] KVM: x86: introduce is_pae_paging Paolo Bonzini
2019-06-13 17:03 ` [PATCH 30/43] KVM: nVMX: Copy PDPTRs to/from vmcs12 only when necessary Paolo Bonzini
2019-06-13 17:03 ` [PATCH 31/43] KVM: nVMX: Use adjusted pin controls for vmcs02 Paolo Bonzini
2019-06-13 17:03 ` [PATCH 32/43] KVM: VMX: Add builder macros for shadowing controls Paolo Bonzini
2019-06-13 17:03 ` [PATCH 33/43] KVM: VMX: Shadow VMCS pin controls Paolo Bonzini
2019-06-13 17:03 ` [PATCH 34/43] KVM: VMX: Shadow VMCS primary execution controls Paolo Bonzini
2019-06-13 17:03 ` [PATCH 35/43] KVM: VMX: Shadow VMCS secondary " Paolo Bonzini
2019-06-13 17:03 ` [PATCH 36/43] KVM: nVMX: Shadow VMCS controls on a per-VMCS basis Paolo Bonzini
2019-06-13 17:03 ` [PATCH 37/43] KVM: nVMX: Don't reset VMCS controls shadow on VMCS switch Paolo Bonzini
2019-06-13 17:03 ` Paolo Bonzini [this message]
2019-06-13 17:03 ` [PATCH 39/43] KVM: nVMX: Preserve last USE_MSR_BITMAPS when preparing vmcs02 Paolo Bonzini
2019-06-13 17:03 ` [PATCH 40/43] KVM: nVMX: Preset *DT exiting in vmcs02 when emulating UMIP Paolo Bonzini
2019-06-13 17:03 ` [PATCH 41/43] KVM: VMX: Drop hv_timer_armed from 'struct loaded_vmcs' Paolo Bonzini
2019-06-13 17:03 ` [PATCH 42/43] KVM: VMX: Leave preemption timer running when it's disabled Paolo Bonzini
2019-06-14 16:34   ` Sean Christopherson
2019-06-13 17:03 ` [PATCH 43/43] KVM: nVMX: shadow pin based execution controls Paolo Bonzini
2019-06-14 16:34   ` Sean Christopherson

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