From f98c1e77127de7d9ff558570c25d02ef077df50f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 1 May 2020 21:32:30 -0700 Subject: [PATCH] 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 Message-Id: <20200502043234.12481-7-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- 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 3ff671e35d76..3e2f582160fe 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, @@ -1092,7 +1093,6 @@ 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 18a63641b612..805297e9a1cb 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1525,10 +1525,6 @@ 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; @@ -4007,7 +4003,6 @@ 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 31a8d04a6c41..83e3fe083679 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2204,6 +2204,8 @@ 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) { @@ -2221,6 +2223,12 @@ 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; @@ -2922,14 +2930,6 @@ 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; @@ -3128,6 +3128,7 @@ 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) { @@ -7809,7 +7810,6 @@ 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 373674d455e1..04bb557acdd2 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; -- GitLab