KVM: x86: Fold decache_cr3() into cache_reg()

Handle caching CR3 (from VMX's VMCS) into struct kvm_vcpu via the common
cache_reg() callback and drop the dedicated decache_cr3().  The name
decache_cr3() is somewhat confusing as the caching behavior of CR3
follows that of GPRs, RFLAGS and PDPTRs, (handled via cache_reg()), and
has nothing in common with the caching behavior of CR0/CR4 (whose
decache_cr{0,4}_guest_bits() likely provided the 'decache' verbiage).

This would effectivel adds a BUG() if KVM attempts to cache CR3 on SVM.
Change it to a WARN_ON_ONCE() -- if the cache never requires filling,
the value is already in the right place -- and opportunistically add one
in VMX to provide an equivalent check.

Signed-off-by: Sean Christopherson <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 c86c95a..cdde748 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1033,7 +1033,6 @@ 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_cr3)(struct kvm_vcpu *vcpu);
        void (*decache_cr4_guest_bits)(struct kvm_vcpu *vcpu);
        void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);
        void (*set_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3);

diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index e85b5ed..5876702 100644 (file)
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -137,7 +137,7 @@ static inline ulong kvm_read_cr4_bits(struct kvm_vcpu *vcpu, ulong mask)
 static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu)
 {
        if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
-               kvm_x86_ops->decache_cr3(vcpu);
+               kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_CR3);
        return vcpu->arch.cr3;
 }
 

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 62b0938..80711b6 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2376,7 +2376,7 @@ static void svm_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
                load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu));
                break;
        default:
-               BUG();
+               WARN_ON_ONCE(1);
        }
 }
 
@@ -2529,10 +2529,6 @@ static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
 {
 }
 
-static void svm_decache_cr3(struct kvm_vcpu *vcpu)
-{
-}
-
 static void svm_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
 {
 }
@@ -7269,7 +7265,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
        .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_cr3 = svm_decache_cr3,
        .decache_cr4_guest_bits = svm_decache_cr4_guest_bits,
        .set_cr0 = svm_set_cr0,
        .set_cr3 = svm_set_cr3,

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 48a41ab..1b022db 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2192,7 +2192,12 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
                if (enable_ept)
                        ept_save_pdptrs(vcpu);
                break;
+       case VCPU_EXREG_CR3:
+               if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))
+                       vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
+               break;
        default:
+               WARN_ON_ONCE(1);
                break;
        }
 }
@@ -2863,13 +2868,6 @@ 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_cr3(struct kvm_vcpu *vcpu)
-{
-       if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))
-               vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
-       kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
-}
-
 static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
 {
        ulong cr4_guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;
@@ -2914,7 +2912,7 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
        if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
-               vmx_decache_cr3(vcpu);
+               vmx_cache_reg(vcpu, VCPU_EXREG_CR3);
        if (!(cr0 & X86_CR0_PG)) {
                /* From paging/starting to nonpaging */
                exec_controls_setbit(vmx, CPU_BASED_CR3_LOAD_EXITING |
@@ -7784,7 +7782,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
        .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_cr3 = vmx_decache_cr3,
        .decache_cr4_guest_bits = vmx_decache_cr4_guest_bits,
        .set_cr0 = vmx_set_cr0,
        .set_cr3 = vmx_set_cr3,