| Message ID | 43b25ff21cd2d9a51582033c9bdd895afefac056.1622730232.git.viremana@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Hyper-V nested virt enlightenments for SVM | expand |
From: Vineeth Pillai <viremana@linux.microsoft.com> Sent: Thursday, June 3, 2021 8:15 AM > > Previously, to detect nested virtualization enlightenment support, > we were using HV_X64_ENLIGHTENED_VMCS_RECOMMENDED feature bit of > HYPERV_CPUID_ENLIGHTMENT_INFO.EAX CPUID as docuemented in TLFS: s/docuemented/documented/ > "Bit 14: Recommend a nested hypervisor using the enlightened VMCS > interface. Also indicates that additional nested enlightenments > may be available (see leaf 0x4000000A)". > > Enlightened VMCS, however, is an Intel only feature so the above > detection method doesn't work for AMD. So, use the > HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS.EAX CPUID information ("The > maximum input value for hypervisor CPUID information.") and this > works for both AMD and Intel. > > Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com> > --- > arch/x86/kernel/cpu/mshyperv.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c > index 22f13343b5da..c268c2730048 100644 > --- a/arch/x86/kernel/cpu/mshyperv.c > +++ b/arch/x86/kernel/cpu/mshyperv.c > @@ -252,6 +252,7 @@ static void __init hv_smp_prepare_cpus(unsigned int max_cpus) > > static void __init ms_hyperv_init_platform(void) > { > + int hv_max_functions_eax; > int hv_host_info_eax; > int hv_host_info_ebx; > int hv_host_info_ecx; > @@ -269,6 +270,8 @@ static void __init ms_hyperv_init_platform(void) > 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, > ms_hyperv.misc_features); > @@ -298,8 +301,7 @@ static void __init ms_hyperv_init_platform(void) > /* > * Extract host information. > */ > - if (cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS) >= > - HYPERV_CPUID_VERSION) { > + if (hv_max_functions_eax >= HYPERV_CPUID_VERSION) { > hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION); > hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION); > hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION); > @@ -325,9 +327,11 @@ static void __init ms_hyperv_init_platform(void) > ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b); > } > > - if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) { > + if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) { > ms_hyperv.nested_features = > cpuid_eax(HYPERV_CPUID_NESTED_FEATURES); > + pr_info("Hyper-V: Nested features: 0x%x\n", Nit: Drop the colon after "Nested features". Current code isn't very consistent but I'm trying to establish the pattern of "Hyper-V:" followed by names and values, with multiple name/value pairs separated by a comma. > + ms_hyperv.nested_features); > } > > /* > -- > 2.25.1 Nits notwithstanding, Reviewed-by: Michael Kelley <mikelley@microsoft.com>
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 22f13343b5da..c268c2730048 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -252,6 +252,7 @@ static void __init hv_smp_prepare_cpus(unsigned int max_cpus) static void __init ms_hyperv_init_platform(void) { + int hv_max_functions_eax; int hv_host_info_eax; int hv_host_info_ebx; int hv_host_info_ecx; @@ -269,6 +270,8 @@ static void __init ms_hyperv_init_platform(void) 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, ms_hyperv.misc_features); @@ -298,8 +301,7 @@ static void __init ms_hyperv_init_platform(void) /* * Extract host information. */ - if (cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS) >= - HYPERV_CPUID_VERSION) { + if (hv_max_functions_eax >= HYPERV_CPUID_VERSION) { hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION); hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION); hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION); @@ -325,9 +327,11 @@ static void __init ms_hyperv_init_platform(void) ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b); } - if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) { + if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) { ms_hyperv.nested_features = cpuid_eax(HYPERV_CPUID_NESTED_FEATURES); + pr_info("Hyper-V: Nested features: 0x%x\n", + ms_hyperv.nested_features); } /*
Previously, to detect nested virtualization enlightenment support, we were using HV_X64_ENLIGHTENED_VMCS_RECOMMENDED feature bit of HYPERV_CPUID_ENLIGHTMENT_INFO.EAX CPUID as docuemented in TLFS: "Bit 14: Recommend a nested hypervisor using the enlightened VMCS interface. Also indicates that additional nested enlightenments may be available (see leaf 0x4000000A)". Enlightened VMCS, however, is an Intel only feature so the above detection method doesn't work for AMD. So, use the HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS.EAX CPUID information ("The maximum input value for hypervisor CPUID information.") and this works for both AMD and Intel. Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com> --- arch/x86/kernel/cpu/mshyperv.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)