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From: John Allen <john.allen@amd.com>
To: <kvm@vger.kernel.org>
CC: <weijiang.yang@intel.com>, <rick.p.edgecombe@intel.com>,
	<seanjc@google.com>, <thomas.lendacky@amd.com>, <bp@alien8.de>,
	<pbonzini@redhat.com>, <mlevitsk@redhat.com>, <linux-kernel@vger.kernel.org>,
	<x86@kernel.org>, John Allen <john.allen@amd.com>
Subject: [PATCH v2 1/9] x86/boot: Move boot_*msr helpers to asm/shared/msr.h
Date: Mon, 26 Feb 2024 21:32:36 +0000
Message-ID: <20240226213244.18441-2-john.allen@amd.com>
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The boot_rdmsr and boot_wrmsr helpers used to reduce the need for inline
assembly in the boot kernel can also be useful in code shared by boot
and run-time kernel code. Move these helpers to asm/shared/msr.h and
rename to raw_rdmsr and raw_wrmsr to indicate that these may also be
used outside of the boot kernel.

Signed-off-by: John Allen <john.allen@amd.com>
---
v2:
  - New in v2
---
 arch/x86/boot/compressed/sev.c    | 10 +++++-----
 arch/x86/boot/cpucheck.c          | 16 ++++++++--------
 arch/x86/boot/msr.h               | 26 --------------------------
 arch/x86/include/asm/shared/msr.h | 15 +++++++++++++++
 4 files changed, 28 insertions(+), 39 deletions(-)
 delete mode 100644 arch/x86/boot/msr.h

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 454acd7a2daf..743b9eb8b7c3 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -13,6 +13,7 @@
 #include "misc.h"
 
 #include <asm/pgtable_types.h>
+#include <asm/shared/msr.h>
 #include <asm/sev.h>
 #include <asm/trapnr.h>
 #include <asm/trap_pf.h>
@@ -23,7 +24,6 @@
 #include <asm/cpuid.h>
 
 #include "error.h"
-#include "../msr.h"
 
 static struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
 struct ghcb *boot_ghcb;
@@ -60,7 +60,7 @@ static inline u64 sev_es_rd_ghcb_msr(void)
 {
 	struct msr m;
 
-	boot_rdmsr(MSR_AMD64_SEV_ES_GHCB, &m);
+	raw_rdmsr(MSR_AMD64_SEV_ES_GHCB, &m);
 
 	return m.q;
 }
@@ -70,7 +70,7 @@ static inline void sev_es_wr_ghcb_msr(u64 val)
 	struct msr m;
 
 	m.q = val;
-	boot_wrmsr(MSR_AMD64_SEV_ES_GHCB, &m);
+	raw_wrmsr(MSR_AMD64_SEV_ES_GHCB, &m);
 }
 
 static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
@@ -482,7 +482,7 @@ void sev_enable(struct boot_params *bp)
 	}
 
 	/* Set the SME mask if this is an SEV guest. */
-	boot_rdmsr(MSR_AMD64_SEV, &m);
+	raw_rdmsr(MSR_AMD64_SEV, &m);
 	sev_status = m.q;
 	if (!(sev_status & MSR_AMD64_SEV_ENABLED))
 		return;
@@ -523,7 +523,7 @@ u64 sev_get_status(void)
 	if (sev_check_cpu_support() < 0)
 		return 0;
 
-	boot_rdmsr(MSR_AMD64_SEV, &m);
+	raw_rdmsr(MSR_AMD64_SEV, &m);
 	return m.q;
 }
 
diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index fed8d13ce252..bb5c28d0a1f1 100644
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -25,9 +25,9 @@
 #include <asm/intel-family.h>
 #include <asm/processor-flags.h>
 #include <asm/required-features.h>
+#include <asm/shared/msr.h>
 #include <asm/msr-index.h>
 #include "string.h"
-#include "msr.h"
 
 static u32 err_flags[NCAPINTS];
 
@@ -133,9 +133,9 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
 
 		struct msr m;
 
-		boot_rdmsr(MSR_K7_HWCR, &m);
+		raw_rdmsr(MSR_K7_HWCR, &m);
 		m.l &= ~(1 << 15);
-		boot_wrmsr(MSR_K7_HWCR, &m);
+		raw_wrmsr(MSR_K7_HWCR, &m);
 
 		get_cpuflags();	/* Make sure it really did something */
 		err = check_cpuflags();
@@ -147,9 +147,9 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
 
 		struct msr m;
 
-		boot_rdmsr(MSR_VIA_FCR, &m);
+		raw_rdmsr(MSR_VIA_FCR, &m);
 		m.l |= (1 << 1) | (1 << 7);
-		boot_wrmsr(MSR_VIA_FCR, &m);
+		raw_wrmsr(MSR_VIA_FCR, &m);
 
 		set_bit(X86_FEATURE_CX8, cpu.flags);
 		err = check_cpuflags();
@@ -159,14 +159,14 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
 		struct msr m, m_tmp;
 		u32 level = 1;
 
-		boot_rdmsr(0x80860004, &m);
+		raw_rdmsr(0x80860004, &m);
 		m_tmp = m;
 		m_tmp.l = ~0;
-		boot_wrmsr(0x80860004, &m_tmp);
+		raw_wrmsr(0x80860004, &m_tmp);
 		asm("cpuid"
 		    : "+a" (level), "=d" (cpu.flags[0])
 		    : : "ecx", "ebx");
-		boot_wrmsr(0x80860004, &m);
+		raw_wrmsr(0x80860004, &m);
 
 		err = check_cpuflags();
 	} else if (err == 0x01 &&
diff --git a/arch/x86/boot/msr.h b/arch/x86/boot/msr.h
deleted file mode 100644
index aed66f7ae199..000000000000
--- a/arch/x86/boot/msr.h
+++ /dev/null
@@ -1,26 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Helpers/definitions related to MSR access.
- */
-
-#ifndef BOOT_MSR_H
-#define BOOT_MSR_H
-
-#include <asm/shared/msr.h>
-
-/*
- * The kernel proper already defines rdmsr()/wrmsr(), but they are not for the
- * boot kernel since they rely on tracepoint/exception handling infrastructure
- * that's not available here.
- */
-static inline void boot_rdmsr(unsigned int reg, struct msr *m)
-{
-	asm volatile("rdmsr" : "=a" (m->l), "=d" (m->h) : "c" (reg));
-}
-
-static inline void boot_wrmsr(unsigned int reg, const struct msr *m)
-{
-	asm volatile("wrmsr" : : "c" (reg), "a"(m->l), "d" (m->h) : "memory");
-}
-
-#endif /* BOOT_MSR_H */
diff --git a/arch/x86/include/asm/shared/msr.h b/arch/x86/include/asm/shared/msr.h
index 1e6ec10b3a15..a20b1c08c99f 100644
--- a/arch/x86/include/asm/shared/msr.h
+++ b/arch/x86/include/asm/shared/msr.h
@@ -12,4 +12,19 @@ struct msr {
 	};
 };
 
+/*
+ * The kernel proper already defines rdmsr()/wrmsr(), but they are not for the
+ * boot kernel since they rely on tracepoint/exception handling infrastructure
+ * that's not available here.
+ */
+static inline void raw_rdmsr(unsigned int reg, struct msr *m)
+{
+	asm volatile("rdmsr" : "=a" (m->l), "=d" (m->h) : "c" (reg));
+}
+
+static inline void raw_wrmsr(unsigned int reg, const struct msr *m)
+{
+	asm volatile("wrmsr" : : "c" (reg), "a"(m->l), "d" (m->h) : "memory");
+}
+
 #endif /* _ASM_X86_SHARED_MSR_H */
-- 
2.40.1