linux-kernel - [PATCH v2] KVM: x86: Advertise SUCCOR and OVERFLOW

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Message-ID: <20240731143649.17082-1-john.allen@amd.com>
Date: Wed, 31 Jul 2024 14:36:49 +0000
From: John Allen <john.allen@....com>
To: <pbonzini@...hat.com>, <kvm@...r.kernel.org>, <seanjc@...gle.com>
CC: <thomas.lendacky@....com>, <bp@...en8.de>, <mlevitsk@...hat.com>,
	<linux-kernel@...r.kernel.org>, <x86@...nel.org>, <yazen.ghannam@....com>,
	John Allen <john.allen@....com>
Subject: [PATCH v2] KVM: x86: Advertise SUCCOR and OVERFLOW_RECOV cpuid bits

Handling deferred, uncorrected MCEs on AMD guests is now possible with
additional support in qemu. Ensure that the SUCCOR and OVERFLOW_RECOV
bits are advertised to the guest in KVM.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: John Allen <john.allen@....com>
---
v2:
  - Add cpuid_entry_override for CPUID_8000_0007_EBX.
  - Handle masking bits in arch/x86/kvm/cpuid.c
---
 arch/x86/kvm/cpuid.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2617be544480..f8e1fd409cee 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -743,6 +743,11 @@ void kvm_set_cpu_caps(void)
 	if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
 		kvm_cpu_cap_set(X86_FEATURE_GBPAGES);
 
+	kvm_cpu_cap_mask(CPUID_8000_0007_EBX,
+		F(OVERFLOW_RECOV) |
+		F(SUCCOR)
+	);
+
 	kvm_cpu_cap_init_kvm_defined(CPUID_8000_0007_EDX,
 		SF(CONSTANT_TSC)
 	);
@@ -1237,11 +1242,12 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		entry->edx &= ~GENMASK(17, 16);
 		break;
 	case 0x80000007: /* Advanced power management */
+		cpuid_entry_override(entry, CPUID_8000_0007_EBX);
 		cpuid_entry_override(entry, CPUID_8000_0007_EDX);
 
 		/* mask against host */
 		entry->edx &= boot_cpu_data.x86_power;
-		entry->eax = entry->ebx = entry->ecx = 0;
+		entry->eax = entry->ecx = 0;
 		break;
 	case 0x80000008: {
 		/*
-- 
2.34.1