x86/mshyperv: Add support for extended Hyper-V features

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>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1741980536-3865-3-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1741980536-3865-3-git-send-email-nunodasneves@linux.microsoft.com>

Author: Stanislav Kinsburskii

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 %#x, high %#x, ext %#x, hints %#x, misc %#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);

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;