linux-kernel - Re: [PATCH 7/7] KVM: TDX: Add TSX_CTRL msr into uret

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Message-ID: <Z0+vdVRptHNX5LPo@intel.com>
Date: Wed, 4 Dec 2024 09:25:09 +0800
From: Chao Gao <chao.gao@...el.com>
To: Adrian Hunter <adrian.hunter@...el.com>
CC: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "Li,
 Xiaoyao" <xiaoyao.li@...el.com>, "Huang, Kai" <kai.huang@...el.com>, "Zhao,
 Yan Y" <yan.y.zhao@...el.com>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Yang, Weijiang" <weijiang.yang@...el.com>,
	"binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>,
	"dmatlack@...gle.com" <dmatlack@...gle.com>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"tony.lindgren@...ux.intel.com" <tony.lindgren@...ux.intel.com>,
	"nik.borisov@...e.com" <nik.borisov@...e.com>, "Chatre, Reinette"
	<reinette.chatre@...el.com>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH 7/7] KVM: TDX: Add TSX_CTRL msr into uret_msrs list

>+#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);
>+}

No need to check TSX/WAITPKG explicitly because setup_tdparams_cpuids() already
ensures that unconfigurable bits are not set by userspace.

>+
> #define KVM_TDX_CPUID_NO_SUBLEAF	((__u32)-1)
> 
> static void td_init_cpuid_entry2(struct kvm_cpuid_entry2 *entry, unsigned char idx)
>@@ -124,6 +162,8 @@ static void td_init_cpuid_entry2(struct kvm_cpuid_entry2 *entry, unsigned char i
> 	/* Work around missing support on old TDX modules */
> 	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,
>@@ -1235,6 +1275,9 @@ 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
>