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Subject[PATCH v2 16/23] x86,vmx: Provide asm-goto-output vmread
Use asm-goto-output for smaller fast path code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/kvm/vmx/vmx_ops.h | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -71,6 +71,31 @@ static __always_inline unsigned long __v
{
unsigned long value;

+#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
+
+ asm_volatile_goto("1: vmread %[field], %[output]\n\t"
+ "jna %l[do_fail]\n\t"
+
+ _ASM_EXTABLE(1b, %l[do_exception])
+
+ : ASM_CALL_CONSTRAINT, [output] "=r" (value)
+ : [field] "r" (field)
+ : "cc"
+ : do_fail, do_exception);
+
+ return value;
+
+do_fail:
+ WARN_ONCE(1, "kvm: vmread failed: field=%lx\n", field);
+ pr_warn_ratelimited("kvm: vmread failed: field=%lx\n", field);
+ return 0;
+
+do_exception:
+ kvm_spurious_fault();
+ return 0;
+
+#else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
+
asm volatile("1: vmread %2, %1\n\t"
".byte 0x3e\n\t" /* branch taken hint */
"ja 3f\n\t"
@@ -99,6 +124,8 @@ static __always_inline unsigned long __v

: ASM_CALL_CONSTRAINT, "=&r"(value) : "r"(field) : "cc");
return value;
+
+#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
}

static __always_inline u16 vmcs_read16(unsigned long field)

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