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Date: Fri, 1 May 2020 21:32:30 -0700
From: Sean Christopherson <sean.j.christopherson@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.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 06/10] KVM: VMX: Add proper cache tracking for CR4
Move CR4 caching into the standard register caching mechanism in order
to take advantage of the availability checks provided by regs_avail.
This avoids multiple VMREADs and retpolines (when configured) during
nested VMX transitions as kvm_read_cr4_bits() is invoked multiple times
on each transition, e.g. when stuffing CR0 and CR3.
As an added bonus, this eliminates a kvm_x86_ops hook, saves a retpoline
on SVM when reading CR4, and squashes the confusing naming discrepancy
of "cache_reg" vs. "decache_cr4_guest_bits".
No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/kvm_cache_regs.h | 5 +++--
arch/x86/kvm/svm/svm.c | 5 -----
arch/x86/kvm/vmx/vmx.c | 18 +++++++++---------
arch/x86/kvm/vmx/vmx.h | 1 +
5 files changed, 14 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d71d1f38b7a0..dbf7d3f2edbc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -168,6 +168,7 @@ enum kvm_reg {
VCPU_EXREG_PDPTR = NR_VCPU_REGS,
VCPU_EXREG_CR3,
+ VCPU_EXREG_CR4,
VCPU_EXREG_RFLAGS,
VCPU_EXREG_SEGMENTS,
VCPU_EXREG_EXIT_INFO_1,
@@ -1091,7 +1092,6 @@ struct kvm_x86_ops {
struct kvm_segment *var, int seg);
void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l);
void (*decache_cr0_guest_bits)(struct kvm_vcpu *vcpu);
- void (*decache_cr4_guest_bits)(struct kvm_vcpu *vcpu);
void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);
int (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4);
void (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index 62558b9bdda7..921a539bcb96 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -129,8 +129,9 @@ static inline ulong kvm_read_cr0(struct kvm_vcpu *vcpu)
static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask)
{
ulong tmask = mask & KVM_POSSIBLE_CR4_GUEST_BITS;
- if (tmask & vcpu->arch.cr4_guest_owned_bits)
- kvm_x86_ops.decache_cr4_guest_bits(vcpu);
+ if ((tmask & vcpu->arch.cr4_guest_owned_bits) &&
+ !kvm_register_is_available(vcpu, VCPU_EXREG_CR4))
+ kvm_x86_ops.cache_reg(vcpu, VCPU_EXREG_CR4);
return vcpu->arch.cr4 & mask;
}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f40a43a288b9..e09f7e8b961f 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1528,10 +1528,6 @@ static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
{
}
-static void svm_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
-{
-}
-
static void update_cr0_intercept(struct vcpu_svm *svm)
{
ulong gcr0 = svm->vcpu.arch.cr0;
@@ -3998,7 +3994,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.get_cpl = svm_get_cpl,
.get_cs_db_l_bits = kvm_get_cs_db_l_bits,
.decache_cr0_guest_bits = svm_decache_cr0_guest_bits,
- .decache_cr4_guest_bits = svm_decache_cr4_guest_bits,
.set_cr0 = svm_set_cr0,
.set_cr4 = svm_set_cr4,
.set_efer = svm_set_efer,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e157bdc218ea..31316cffb427 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2187,6 +2187,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
{
+ unsigned long guest_owned_bits;
+
kvm_register_mark_available(vcpu, reg);
switch (reg) {
@@ -2204,6 +2206,12 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))
vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
break;
+ case VCPU_EXREG_CR4:
+ guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;
+
+ vcpu->arch.cr4 &= ~guest_owned_bits;
+ vcpu->arch.cr4 |= vmcs_readl(GUEST_CR4) & guest_owned_bits;
+ break;
default:
WARN_ON_ONCE(1);
break;
@@ -2905,14 +2913,6 @@ static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & cr0_guest_owned_bits;
}
-static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
-{
- ulong cr4_guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;
-
- vcpu->arch.cr4 &= ~cr4_guest_owned_bits;
- vcpu->arch.cr4 |= vmcs_readl(GUEST_CR4) & cr4_guest_owned_bits;
-}
-
static void ept_load_pdptrs(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
@@ -3111,6 +3111,7 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
return 1;
vcpu->arch.cr4 = cr4;
+ kvm_register_mark_available(vcpu, VCPU_EXREG_CR4);
if (!enable_unrestricted_guest) {
if (enable_ept) {
@@ -7782,7 +7783,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
.get_cpl = vmx_get_cpl,
.get_cs_db_l_bits = vmx_get_cs_db_l_bits,
.decache_cr0_guest_bits = vmx_decache_cr0_guest_bits,
- .decache_cr4_guest_bits = vmx_decache_cr4_guest_bits,
.set_cr0 = vmx_set_cr0,
.set_cr4 = vmx_set_cr4,
.set_efer = vmx_set_efer,
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index fa61dc802183..39d0f32372e7 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -453,6 +453,7 @@ static inline void vmx_register_cache_reset(struct kvm_vcpu *vcpu)
| (1 << VCPU_EXREG_PDPTR)
| (1 << VCPU_EXREG_SEGMENTS)
| (1 << VCPU_EXREG_CR3)
+ | (1 << VCPU_EXREG_CR4)
| (1 << VCPU_EXREG_EXIT_INFO_1)
| (1 << VCPU_EXREG_EXIT_INFO_2));
vcpu->arch.regs_dirty = 0;
--
2.26.0
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