From: Adrian Hunter <adrian.hunter@intel.com>
Date: Wed, 29 Jan 2025 09:58:59 +0000 (+0200)
Subject: KVM: TDX: Disable support for TSX and WAITPKG
X-Git-Tag: v6.16-rc1~78^2~17^2~3^2~2
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=6d415778f1069b52344f7cb09ae7b623579486c9;p=linux-2.6-block.git

KVM: TDX: Disable support for TSX and WAITPKG

Support for restoring IA32_TSX_CTRL MSR and IA32_UMWAIT_CONTROL MSR is not
yet implemented, so disable support for TSX and WAITPKG for now.  Clear the
associated CPUID bits returned by KVM_TDX_CAPABILITIES, and return an error
if those bits are set in KVM_TDX_INIT_VM.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Message-ID: <20250129095902.16391-11-adrian.hunter@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index b942678677cc..06decfe9eb5e 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -107,6 +107,44 @@ static u32 tdx_set_guest_phys_addr_bits(const u32 eax, int addr_bits)
 	return (eax & ~GENMASK(23, 16)) | (addr_bits & 0xff) << 16;
 }
 
+#define TDX_FEATURE_TSX (__feature_bit(X86_FEATURE_HLE) | __feature_bit(X86_FEATURE_RTM))
+
+static bool has_tsx(const struct kvm_cpuid_entry2 *entry)
+{
+	return entry->function == 7 && entry->index == 0 &&
+	       (entry->ebx & TDX_FEATURE_TSX);
+}
+
+static void clear_tsx(struct kvm_cpuid_entry2 *entry)
+{
+	entry->ebx &= ~TDX_FEATURE_TSX;
+}
+
+static bool has_waitpkg(const struct kvm_cpuid_entry2 *entry)
+{
+	return entry->function == 7 && entry->index == 0 &&
+	       (entry->ecx & __feature_bit(X86_FEATURE_WAITPKG));
+}
+
+static void clear_waitpkg(struct kvm_cpuid_entry2 *entry)
+{
+	entry->ecx &= ~__feature_bit(X86_FEATURE_WAITPKG);
+}
+
+static void tdx_clear_unsupported_cpuid(struct kvm_cpuid_entry2 *entry)
+{
+	if (has_tsx(entry))
+		clear_tsx(entry);
+
+	if (has_waitpkg(entry))
+		clear_waitpkg(entry);
+}
+
+static bool tdx_unsupported_cpuid(const struct kvm_cpuid_entry2 *entry)
+{
+	return has_tsx(entry) || has_waitpkg(entry);
+}
+
 #define KVM_TDX_CPUID_NO_SUBLEAF	((__u32)-1)
 
 static void td_init_cpuid_entry2(struct kvm_cpuid_entry2 *entry, unsigned char idx)
@@ -130,6 +168,8 @@ static void td_init_cpuid_entry2(struct kvm_cpuid_entry2 *entry, unsigned char i
 	 */
 	if (entry->function == 0x80000008)
 		entry->eax = tdx_set_guest_phys_addr_bits(entry->eax, 0xff);
+
+	tdx_clear_unsupported_cpuid(entry);
 }
 
 static int init_kvm_tdx_caps(const struct tdx_sys_info_td_conf *td_conf,
@@ -1244,6 +1284,9 @@ static int setup_tdparams_cpuids(struct kvm_cpuid2 *cpuid,
 		if (!entry)
 			continue;
 
+		if (tdx_unsupported_cpuid(entry))
+			return -EINVAL;
+
 		copy_cnt++;
 
 		value = &td_params->cpuid_values[i];