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Date: Thu, 4 Jan 2024 15:42:02 +0100
From: Borislav Petkov <bp@alien8.de>
To: Michael Roth <michael.roth@amd.com>
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	Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v1 04/26] x86/sev: Add the host SEV-SNP initialization
 support
Message-ID: <20240104144202.GGZZbDuutFUFmktT7M@fat_crate.local>
References: <20231230161954.569267-1-michael.roth@amd.com>
 <20231230161954.569267-5-michael.roth@amd.com>
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In-Reply-To: <20231230161954.569267-5-michael.roth@amd.com>

On Sat, Dec 30, 2023 at 10:19:32AM -0600, Michael Roth wrote:
> +	if (cpu_has(c, X86_FEATURE_SEV_SNP)) {
> +		/*
> +		 * RMP table entry format is not architectural and it can vary by processor
> +		 * and is defined by the per-processor PPR. Restrict SNP support on the
> +		 * known CPU model and family for which the RMP table entry format is
> +		 * currently defined for.
> +		 */
> +		if (!(c->x86 == 0x19 && c->x86_model <= 0xaf) &&
> +		    !(c->x86 == 0x1a && c->x86_model <= 0xf))
> +			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
> +		else if (!snp_probe_rmptable_info())
> +			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
> +	}

IOW, this below.

Lemme send the ZEN5 thing as a separate patch.

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 9492dcad560d..0fa702673e73 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -81,10 +81,8 @@
 #define X86_FEATURE_K6_MTRR		( 3*32+ 1) /* AMD K6 nonstandard MTRRs */
 #define X86_FEATURE_CYRIX_ARR		( 3*32+ 2) /* Cyrix ARRs (= MTRRs) */
 #define X86_FEATURE_CENTAUR_MCR		( 3*32+ 3) /* Centaur MCRs (= MTRRs) */
-
-/* CPU types for specific tunings: */
 #define X86_FEATURE_K8			( 3*32+ 4) /* "" Opteron, Athlon64 */
-/* FREE, was #define X86_FEATURE_K7			( 3*32+ 5) "" Athlon */
+#define X86_FEATURE_ZEN5		( 3*32+ 5) /* "" CPU based on Zen5 microarchitecture */
 #define X86_FEATURE_P3			( 3*32+ 6) /* "" P3 */
 #define X86_FEATURE_P4			( 3*32+ 7) /* "" P4 */
 #define X86_FEATURE_CONSTANT_TSC	( 3*32+ 8) /* TSC ticks at a constant rate */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 0f0d425f0440..46335c2df083 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -539,7 +539,7 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 
 	/* Figure out Zen generations: */
 	switch (c->x86) {
-	case 0x17: {
+	case 0x17:
 		switch (c->x86_model) {
 		case 0x00 ... 0x2f:
 		case 0x50 ... 0x5f:
@@ -555,8 +555,8 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 			goto warn;
 		}
 		break;
-	}
-	case 0x19: {
+
+	case 0x19:
 		switch (c->x86_model) {
 		case 0x00 ... 0x0f:
 		case 0x20 ... 0x5f:
@@ -570,20 +570,31 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 			goto warn;
 		}
 		break;
-	}
+
+	case 0x1a:
+		switch (c->x86_model) {
+		case 0x00 ... 0x0f:
+			setup_force_cpu_cap(X86_FEATURE_ZEN5);
+			break;
+		default:
+			goto warn;
+		}
+		break;
+
 	default:
 		break;
 	}
 
 	if (cpu_has(c, X86_FEATURE_SEV_SNP)) {
 		/*
-		 * RMP table entry format is not architectural and it can vary by processor
+		 * RMP table entry format is not architectural, can vary by processor
 		 * and is defined by the per-processor PPR. Restrict SNP support on the
 		 * known CPU model and family for which the RMP table entry format is
 		 * currently defined for.
 		 */
-		if (!(c->x86 == 0x19 && c->x86_model <= 0xaf) &&
-		    !(c->x86 == 0x1a && c->x86_model <= 0xf))
+		if (!boot_cpu_has(X86_FEATURE_ZEN3) &&
+		    !boot_cpu_has(X86_FEATURE_ZEN4) &&
+		    !boot_cpu_has(X86_FEATURE_ZEN5))
 			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
 		else if (!snp_probe_rmptable_info())
 			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
@@ -1055,6 +1066,11 @@ static void init_amd_zen4(struct cpuinfo_x86 *c)
 		msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT);
 }
 
+static void init_amd_zen5(struct cpuinfo_x86 *c)
+{
+	init_amd_zen_common();
+}
+
 static void init_amd(struct cpuinfo_x86 *c)
 {
 	u64 vm_cr;
@@ -1100,6 +1116,8 @@ static void init_amd(struct cpuinfo_x86 *c)
 		init_amd_zen3(c);
 	else if (boot_cpu_has(X86_FEATURE_ZEN4))
 		init_amd_zen4(c);
+	else if (boot_cpu_has(X86_FEATURE_ZEN5))
+		init_amd_zen5(c);
 
 	/*
 	 * Enable workaround for FXSAVE leak on CPUs


-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette