KVM: VMX: Add proper cache tracking for CR0

Move CR0 caching into the standard register caching mechanism in order
to take advantage of the availability checks provided by regs_avail.
This avoids multiple VMREADs in the (uncommon) case where kvm_read_cr0()
is called multiple times in a single VM-Exit, and more importantly
eliminates a kvm_x86_ops hook, saves a retpoline on SVM when reading
CR0, and squashes the confusing naming discrepancy of "cache_reg" vs.
"decache_cr0_guest_bits".

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200502043234.12481-8-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3e2f582160fec4683c0ebad14369b36408ba798b..ad882127079f1f62760517f187705f0d2ae24acf 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -167,6 +167,7 @@ enum kvm_reg {
        NR_VCPU_REGS,
 
        VCPU_EXREG_PDPTR = NR_VCPU_REGS,
+       VCPU_EXREG_CR0,
        VCPU_EXREG_CR3,
        VCPU_EXREG_CR4,
        VCPU_EXREG_RFLAGS,
@@ -1092,7 +1093,6 @@ struct kvm_x86_ops {
        void (*set_segment)(struct kvm_vcpu *vcpu,
                            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 (*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 921a539bcb96b10b359c9de5da95e7249f14e05b..ff2d0e9ca3bc0dc45b485e8c406be95bd7581f48 100644 (file)
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -116,8 +116,9 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
 static inline ulong kvm_read_cr0_bits(struct kvm_vcpu *vcpu, ulong mask)
 {
        ulong tmask = mask & KVM_POSSIBLE_CR0_GUEST_BITS;
-       if (tmask & vcpu->arch.cr0_guest_owned_bits)
-               kvm_x86_ops.decache_cr0_guest_bits(vcpu);
+       if ((tmask & vcpu->arch.cr0_guest_owned_bits) &&
+           !kvm_register_is_available(vcpu, VCPU_EXREG_CR0))
+               kvm_x86_ops.cache_reg(vcpu, VCPU_EXREG_CR0);
        return vcpu->arch.cr0 & mask;
 }
 

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 805297e9a1cbe3faf491c0b00bae8985356a2d6d..9e24b5b6fae1e759f15858be134d2de19fd3818d 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1521,10 +1521,6 @@ static void svm_set_gdt(struct kvm_vcpu *vcpu, struct desc_ptr *dt)
        mark_dirty(svm->vmcb, VMCB_DT);
 }
 
-static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
-{
-}
-
 static void update_cr0_intercept(struct vcpu_svm *svm)
 {
        ulong gcr0 = svm->vcpu.arch.cr0;
@@ -4002,7 +3998,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
        .set_segment = svm_set_segment,
        .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,
        .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 83e3fe08367903bf0f8996d364a731c7a4b5d144..a7dca7e305b4c932d9bff54e25663f3321e19bd3 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2219,6 +2219,12 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
                if (enable_ept)
                        ept_save_pdptrs(vcpu);
                break;
+       case VCPU_EXREG_CR0:
+               guest_owned_bits = vcpu->arch.cr0_guest_owned_bits;
+
+               vcpu->arch.cr0 &= ~guest_owned_bits;
+               vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & guest_owned_bits;
+               break;
        case VCPU_EXREG_CR3:
                if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))
                        vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
@@ -2922,14 +2928,6 @@ static void vmx_flush_tlb_guest(struct kvm_vcpu *vcpu)
        vpid_sync_context(to_vmx(vcpu)->vpid);
 }
 
-static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
-{
-       ulong cr0_guest_owned_bits = vcpu->arch.cr0_guest_owned_bits;
-
-       vcpu->arch.cr0 &= ~cr0_guest_owned_bits;
-       vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & cr0_guest_owned_bits;
-}
-
 static void ept_load_pdptrs(struct kvm_vcpu *vcpu)
 {
        struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
@@ -3019,6 +3017,7 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
        vmcs_writel(CR0_READ_SHADOW, cr0);
        vmcs_writel(GUEST_CR0, hw_cr0);
        vcpu->arch.cr0 = cr0;
+       kvm_register_mark_available(vcpu, VCPU_EXREG_CR0);
 
        /* depends on vcpu->arch.cr0 to be set to a new value */
        vmx->emulation_required = emulation_required(vcpu);
@@ -7809,7 +7808,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
        .set_segment = vmx_set_segment,
        .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,
        .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 04bb557acdd238c4d9be52ffe2c6aa4862bfb5c9..298ddef79d0093f5e796851c6aba09da3765d9bc 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -452,6 +452,7 @@ static inline void vmx_register_cache_reset(struct kvm_vcpu *vcpu)
                                  | (1 << VCPU_EXREG_RFLAGS)
                                  | (1 << VCPU_EXREG_PDPTR)
                                  | (1 << VCPU_EXREG_SEGMENTS)
+                                 | (1 << VCPU_EXREG_CR0)
                                  | (1 << VCPU_EXREG_CR3)
                                  | (1 << VCPU_EXREG_CR4)
                                  | (1 << VCPU_EXREG_EXIT_INFO_1)