linux-kernel - [PATCH 2/3] x86/cpu/amd: Add feature bit for MSR_AMD64_LS

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Date:   Mon, 12 Sep 2022 16:40:47 -0700
From:   Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>, degoede@...hat.com
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        antonio.gomez.iglesias@...ux.intel.com
Subject: [PATCH 2/3] x86/cpu/amd: Add feature bit for MSR_AMD64_LS_CFG
 enumeration

Currently there is no easy way to enumerate MSR_AMD64_LS_CFG. As this
MSR is supported on AMD CPU families 10h to 18h, set a new feature bit
on these CPU families. The new bit can be used to detect the MSR
support.

Suggested-by: Andrew Cooper <andrew.cooper3@...rix.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/amd.c          | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index dd173733e40d..90bdb1d98531 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -305,6 +305,7 @@
 #define X86_FEATURE_USE_IBPB_FW		(11*32+16) /* "" Use IBPB during runtime firmware calls */
 #define X86_FEATURE_RSB_VMEXIT_LITE	(11*32+17) /* "" Fill RSB on VM exit when EIBRS is enabled */
 #define X86_FEATURE_MSR_TSX_CTRL	(11*32+18) /* "" MSR IA32_TSX_CTRL */
+#define X86_FEATURE_MSR_LS_CFG		(11*32+19) /* "" MSR AMD64_LS_CFG */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 48276c0e479d..88f59d630826 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -521,6 +521,9 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 		__max_die_per_package = nodes_per_socket = ((value >> 3) & 7) + 1;
 	}
 
+	if (c->x86 >= 0x10 && c->x86 <= 0x18)
+		setup_force_cpu_cap(X86_FEATURE_MSR_LS_CFG);
+
 	if (!boot_cpu_has(X86_FEATURE_AMD_SSBD) &&
 	    !boot_cpu_has(X86_FEATURE_VIRT_SSBD) &&
 	    c->x86 >= 0x15 && c->x86 <= 0x17) {
-- 
2.37.2