x86/boot: Move boot_*msr helpers to asm/shared/msr.h

The boot_{rdmsr,wrmsr}() helpers are *just* the barebones MSR access
functionality, without any tracing or exception handling glue as it is done in
kernel proper.

Move these helpers to asm/shared/msr.h and rename to raw_{rdmsr,wrmsr}() to
indicate what they are.

  [ bp: Correct the reason why those helpers exist. I should've caught that in
    the original patch that added them:
      176db622573f ("x86/boot: Introduce helpers for MSR reads/writes"
    but oh well...
    - fixup include path delimiters to <> ]

Signed-off-by: John Allen <john.allen@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://patch.msgid.link/all/20250924200852.4452-2-john.allen@amd.com

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 6e5c32a53d0342e905f5eb4531a1b337f17616b9..c8c1464b3a56e72816ec76ce826890e2c4c976a5 100644 (file)
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -14,6 +14,7 @@
 
 #include <asm/bootparam.h>
 #include <asm/pgtable_types.h>
+#include <asm/shared/msr.h>
 #include <asm/sev.h>
 #include <asm/trapnr.h>
 #include <asm/trap_pf.h>
@@ -397,7 +398,7 @@ 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;
@@ -446,7 +447,7 @@ 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;
 }
 
@@ -496,7 +497,7 @@ bool early_is_sevsnp_guest(void)
                        struct msr m;
 
                        /* Obtain the address of the calling area to use */
-                       boot_rdmsr(MSR_SVSM_CAA, &m);
+                       raw_rdmsr(MSR_SVSM_CAA, &m);
                        boot_svsm_caa_pa = m.q;
 
                        /*

diff --git a/arch/x86/boot/compressed/sev.h b/arch/x86/boot/compressed/sev.h
index 92f79c21939cc00aedb0df8bfec79320bab51a04..22637b416b46fc2197e0afda8e86d23fe24f6416 100644 (file)
--- a/arch/x86/boot/compressed/sev.h
+++ b/arch/x86/boot/compressed/sev.h
@@ -10,7 +10,7 @@
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 
-#include "../msr.h"
+#include <asm/shared/msr.h>
 
 void snp_accept_memory(phys_addr_t start, phys_addr_t end);
 u64 sev_get_status(void);
@@ -20,7 +20,7 @@ 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;
 }
@@ -30,7 +30,7 @@ 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);
 }
 
 #else

diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index f82de8de5dc62ea8a7f76f011d2de3cea1f9f234..2e1bb936cba2ec3a4c1421eb43f73fe3b54ac34e 100644 (file)
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -26,9 +26,9 @@
 #include <asm/intel-family.h>
 #include <asm/processor-flags.h>
 #include <asm/msr-index.h>
+#include <asm/shared/msr.h>
 
 #include "string.h"
-#include "msr.h"
 
 static u32 err_flags[NCAPINTS];
 
@@ -134,9 +134,9 @@ 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();
@@ -148,9 +148,9 @@ 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();
@@ -160,14 +160,14 @@ 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 (file)
index aed66f7..0000000
--- 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 1e6ec10b3a151218a55049f324a6e1236ad6489f..a20b1c08c99fd7d93dd1f09e23afd3e5728d8f3c 100644 (file)
--- 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 */