[PATCH v1 1/5] x86/cpufeatures: Add CPUID feature bit for Idle HLT intercept

Manali Shukla
2024-03-07T05:46:47Z

From: Manali Shukla <Manali.Shukla@amd.com>

The Idle HLT Intercept feature allows for the HLT instruction
execution by a vCPU to be intercepted by the hypervisor only if there
are no pending events (V_INTR and V_NMI) for the vCPU. When the vCPU
is expected to service the pending events (V_INTR and V_NMI), the Idle
HLT intercept won’t trigger. The feature allows the hypervisor to
determine if the vCPU is idle and reduces wasteful VMEXITs.

Presence of the Idle HLT intercept feature for guests is indicated via
CPUID function 0x8000000A_EDX[30].

Signed-off-by: Manali Shukla <Manali.Shukla@amd.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index fdf723b6f6d0..c312b0bfec6a 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -379,6 +379,7 @@
#define X86_FEATURE_V_SPEC_CTRL (15*32+20) /* Virtual SPEC_CTRL */
#define X86_FEATURE_VNMI (15*32+25) /* Virtual NMI */
#define X86_FEATURE_SVME_ADDR_CHK (15*32+28) /* "" SVME addr check */
+#define X86_FEATURE_IDLE_HLT (15*32+30) /* "" IDLE HLT intercept */

/* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
#define X86_FEATURE_AVX512VBMI (16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
--
2.34.1