linux-kernel - [PATCH V2 10/12] KVM: TDX: Disable support for TSX and WAITPKG

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Message-ID: <20250129095902.16391-11-adrian.hunter@intel.com>
Date: Wed, 29 Jan 2025 11:58:59 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: pbonzini@...hat.com,
	seanjc@...gle.com
Cc: kvm@...r.kernel.org,
	rick.p.edgecombe@...el.com,
	kai.huang@...el.com,
	adrian.hunter@...el.com,
	reinette.chatre@...el.com,
	xiaoyao.li@...el.com,
	tony.lindgren@...ux.intel.com,
	binbin.wu@...ux.intel.com,
	dmatlack@...gle.com,
	isaku.yamahata@...el.com,
	nik.borisov@...e.com,
	linux-kernel@...r.kernel.org,
	yan.y.zhao@...el.com,
	chao.gao@...el.com,
	weijiang.yang@...el.com
Subject: [PATCH V2 10/12] 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@...el.com>
---
TD vcpu enter/exit v2:
 - New patch
---
 arch/x86/kvm/vmx/tdx.c | 43 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index a0f5cdfd290b..70996af4be64 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -117,6 +117,44 @@ 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)
@@ -140,6 +178,8 @@ 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,
@@ -1214,6 +1254,9 @@ 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];
-- 
2.43.0