[PATCH v5 02/10] x86/mshyperv: Add support for extended Hyper-V features

Nuno Das Neves
2025-02-26T23:08:59Z

From: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>

Extend the "ms_hyperv_info" structure to include a new field,
"ext_features", for capturing extended Hyper-V features.
Update the "ms_hyperv_init_platform" function to retrieve these features
using the cpuid instruction and include them in the informational output.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
---
arch/x86/kernel/cpu/mshyperv.c | 6 ++++--
include/asm-generic/mshyperv.h | 1 +
2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 4f01f424ea5b..2c29dfd6de19 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -434,13 +434,15 @@ static void __init ms_hyperv_init_platform(void)
*/
ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
ms_hyperv.priv_high = cpuid_ebx(HYPERV_CPUID_FEATURES);
+ ms_hyperv.ext_features = cpuid_ecx(HYPERV_CPUID_FEATURES);
ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);

hv_max_functions_eax = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);

- pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
- ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
+ pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, ext 0x%x, hints 0x%x, misc 0x%x\n",
+ ms_hyperv.features, ms_hyperv.priv_high,
+ ms_hyperv.ext_features, ms_hyperv.hints,
ms_hyperv.misc_features);

ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index dc4729dba9ef..c020d5d0ec2a 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -36,6 +36,7 @@ enum hv_partition_type {
struct ms_hyperv_info {
u32 features;
u32 priv_high;
+ u32 ext_features;
u32 misc_features;
u32 hints;
u32 nested_features;
--
2.34.1