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authorSean Christopherson <sean.j.christopherson@intel.com>2019-01-25 07:41:03 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-02-12 13:12:23 +0100
commit47e97c099bbcb3211b22456679991095c0578da2 (patch)
tree554332f189cc233cf4dadef626b416f7ec7850fe
parent5a8781607e677eda60b20e0a4c91d2a5f12f9244 (diff)
downloadlinux-stericsson-47e97c099bbcb3211b22456679991095c0578da2.tar.gz
KVM: VMX: Load/save guest CR2 via C code in __vmx_vcpu_run()
...to eliminate its parameter and struct vcpu_vmx offset definition from the assembly blob. Accessing CR2 from C versus assembly doesn't change the likelihood of taking a page fault (and modifying CR2) while it's loaded with the guest's value, so long as we don't do anything silly between accessing CR2 and VM-Enter/VM-Exit. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/vmx/vmx.c16
1 files changed, 5 insertions, 11 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 12bb61e7aca6..5e43999ece1d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6375,6 +6375,9 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
if (static_branch_unlikely(&vmx_l1d_should_flush))
vmx_l1d_flush(vcpu);
+ if (vcpu->arch.cr2 != read_cr2())
+ write_cr2(vcpu->arch.cr2);
+
asm(
/* Store host registers */
"push %%" _ASM_BP " \n\t"
@@ -6395,13 +6398,6 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
"1: \n\t"
"add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */
- /* Reload cr2 if changed */
- "mov %c[cr2](%%" _ASM_CX "), %%" _ASM_AX " \n\t"
- "mov %%cr2, %%" _ASM_DX " \n\t"
- "cmp %%" _ASM_AX ", %%" _ASM_DX " \n\t"
- "je 3f \n\t"
- "mov %%" _ASM_AX", %%cr2 \n\t"
- "3: \n\t"
/* Check if vmlaunch or vmresume is needed */
"cmpb $0, %c[launched](%%" _ASM_CX ") \n\t"
/* Load guest registers. Don't clobber flags. */
@@ -6471,9 +6467,6 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
"xor %%r14d, %%r14d \n\t"
"xor %%r15d, %%r15d \n\t"
#endif
- "mov %%cr2, %%" _ASM_AX " \n\t"
- "mov %%" _ASM_AX ", %c[cr2](%%" _ASM_CX ") \n\t"
-
"xor %%eax, %%eax \n\t"
"xor %%ebx, %%ebx \n\t"
"xor %%ecx, %%ecx \n\t"
@@ -6504,7 +6497,6 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
[r14]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_R14])),
[r15]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_R15])),
#endif
- [cr2]"i"(offsetof(struct vcpu_vmx, vcpu.arch.cr2)),
[wordsize]"i"(sizeof(ulong))
: "cc", "memory"
#ifdef CONFIG_X86_64
@@ -6514,6 +6506,8 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
, "eax", "ebx", "edx"
#endif
);
+
+ vcpu->arch.cr2 = read_cr2();
}
STACK_FRAME_NON_STANDARD(__vmx_vcpu_run);