We clean up a failed VMREAD by clearing the output register. Do
it in the exception handler instead of unconditionally. This is
worthwhile since there are more than a hundred call sites.
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 6 +++++-
arch/x86/kvm/vmx.c | 8 +++++---
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d2ac8e2..db4b654 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -830,11 +830,12 @@ enum {
asmlinkage void kvm_spurious_fault(void);
extern bool kvm_rebooting;
-#define __kvm_handle_fault_on_reboot(insn) \
+#define ____kvm_handle_fault_on_reboot(insn, cleanup_insn) \
"666: " insn "\n\t" \
"668: \n\t" \
".pushsection .fixup, \"ax\" \n" \
"667: \n\t" \
+ cleanup_insn "\n\t" \
"cmpb $0, kvm_rebooting \n\t" \
"jne 668b \n\t" \
__ASM_SIZE(push) " $666b \n\t" \
@@ -844,6 +845,9 @@ extern bool kvm_rebooting;
_ASM_PTR " 666b, 667b \n\t" \
".popsection"
+#define __kvm_handle_fault_on_reboot(insn) \
+ ____kvm_handle_fault_on_reboot(insn, "")
+
#define KVM_ARCH_WANT_MMU_NOTIFIER
int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);
int kvm_age_hva(struct kvm *kvm, unsigned long hva);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4c3fa0f..3df6b2c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -43,6 +43,8 @@
#include "trace.h"
#define __ex(x) __kvm_handle_fault_on_reboot(x)
+#define __ex_clear(x, reg) \
+ ____kvm_handle_fault_on_reboot(x, "xor " reg " , " reg)
MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");
@@ -587,10 +589,10 @@ static inline void ept_sync_individual_addr(u64 eptp, gpa_t gpa)
static unsigned long vmcs_readl(unsigned long field)
{
- unsigned long value = 0;
+ unsigned long value;
- asm volatile (__ex(ASM_VMX_VMREAD_RDX_RAX)
- : "+a"(value) : "d"(field) : "cc");
+ asm volatile (__ex_clear(ASM_VMX_VMREAD_RDX_RAX, "%0")
+ : "=a"(value) : "d"(field) : "cc");
return value;
}
--
1.7.4.3
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