[PATCH v4 13/18] x86/paravirt: Split off MSR related hooks into new header
From: Juergen Gross
Date: Mon Jun 29 2026 - 03:12:32 EST
Move the WRMSR, RDMSR and RDPMC related parts of paravirt.h and
paravirt_types.h into a new header file paravirt-msr.h.
Switch all moved helper functions to __always_inline.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V3:
- new patch
V4:
- always use __always_inline
---
arch/x86/include/asm/msr.h | 2 +-
arch/x86/include/asm/paravirt-msr.h | 56 +++++++++++++++++++++++++++
arch/x86/include/asm/paravirt.h | 55 --------------------------
arch/x86/include/asm/paravirt_types.h | 13 -------
arch/x86/kernel/paravirt.c | 14 ++++---
arch/x86/xen/enlighten_pv.c | 11 +++---
tools/objtool/check.c | 1 +
7 files changed, 73 insertions(+), 79 deletions(-)
create mode 100644 arch/x86/include/asm/paravirt-msr.h
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 6a8af80305d1..b13b4a93673e 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -323,7 +323,7 @@ static inline u64 native_read_pmc(int counter)
}
#ifdef CONFIG_PARAVIRT_XXL
-#include <asm/paravirt.h>
+#include <asm/paravirt-msr.h>
#else
static __always_inline u64 read_msr(u32 msr)
{
diff --git a/arch/x86/include/asm/paravirt-msr.h b/arch/x86/include/asm/paravirt-msr.h
new file mode 100644
index 000000000000..3e31648316a8
--- /dev/null
+++ b/arch/x86/include/asm/paravirt-msr.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_X86_PARAVIRT_MSR_H
+#define _ASM_X86_PARAVIRT_MSR_H
+
+#include <asm/paravirt_types.h>
+
+struct pv_msr_ops {
+ /* Unsafe MSR operations. These will warn or panic on failure. */
+ u64 (*read_msr)(u32 msr);
+ void (*write_msr)(u32 msr, u64 val);
+
+ /* Safe MSR operations. Returns 0 or -EIO. */
+ int (*read_msr_safe)(u32 msr, u64 *val);
+ int (*write_msr_safe)(u32 msr, u64 val);
+
+ u64 (*read_pmc)(int counter);
+} __no_randomize_layout;
+
+extern struct pv_msr_ops pv_ops_msr;
+
+static __always_inline u64 read_msr(u32 msr)
+{
+ return PVOP_CALL1(u64, pv_ops_msr, read_msr, msr);
+}
+
+static __always_inline void write_msr(u32 msr, u64 val)
+{
+ PVOP_VCALL2(pv_ops_msr, write_msr, msr, val);
+}
+
+static __always_inline void write_msrns(u32 msr, u64 val)
+{
+ PVOP_VCALL2(pv_ops_msr, write_msr, msr, val);
+}
+
+static __always_inline int read_msr_safe(u32 msr, u64 *val)
+{
+ return PVOP_CALL2(int, pv_ops_msr, read_msr_safe, msr, val);
+}
+
+static __always_inline int write_msr_safe(u32 msr, u64 val)
+{
+ return PVOP_CALL2(int, pv_ops_msr, write_msr_safe, msr, val);
+}
+
+static __always_inline int write_msrns_safe(u32 msr, u64 val)
+{
+ return PVOP_CALL2(int, pv_ops_msr, write_msr_safe, msr, val);
+}
+
+static __always_inline u64 rdpmc(int counter)
+{
+ return PVOP_CALL1(u64, pv_ops_msr, read_pmc, counter);
+}
+
+#endif /* _ASM_X86_PARAVIRT_MSR_H */
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index b0c740316cf7..eb16d55f94d3 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -130,61 +130,6 @@ static inline void __write_cr4(unsigned long x)
PVOP_VCALL1(pv_ops, cpu.write_cr4, x);
}
-static inline u64 paravirt_read_msr(u32 msr)
-{
- return PVOP_CALL1(u64, pv_ops, cpu.read_msr, msr);
-}
-
-static inline void paravirt_write_msr(u32 msr, u64 val)
-{
- PVOP_VCALL2(pv_ops, cpu.write_msr, msr, val);
-}
-
-static inline int paravirt_read_msr_safe(u32 msr, u64 *val)
-{
- return PVOP_CALL2(int, pv_ops, cpu.read_msr_safe, msr, val);
-}
-
-static inline int paravirt_write_msr_safe(u32 msr, u64 val)
-{
- return PVOP_CALL2(int, pv_ops, cpu.write_msr_safe, msr, val);
-}
-
-static __always_inline u64 read_msr(u32 msr)
-{
- return paravirt_read_msr(msr);
-}
-
-static inline void write_msr(u32 msr, u64 val)
-{
- paravirt_write_msr(msr, val);
-}
-
-static __always_inline void write_msrns(u32 msr, u64 val)
-{
- paravirt_write_msr(msr, val);
-}
-
-static inline int write_msr_safe(u32 msr, u64 val)
-{
- return paravirt_write_msr_safe(msr, val);
-}
-
-static __always_inline int write_msrns_safe(u32 msr, u64 val)
-{
- return paravirt_write_msr_safe(msr, val);
-}
-
-static __always_inline int read_msr_safe(u32 msr, u64 *p)
-{
- return paravirt_read_msr_safe(msr, p);
-}
-
-static __always_inline u64 rdpmc(int counter)
-{
- return PVOP_CALL1(u64, pv_ops, cpu.read_pmc, counter);
-}
-
static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
{
PVOP_VCALL2(pv_ops, cpu.alloc_ldt, ldt, entries);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index b4c4a23e77a1..2459163fa196 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -58,19 +58,6 @@ struct pv_cpu_ops {
void (*cpuid)(unsigned int *eax, unsigned int *ebx,
unsigned int *ecx, unsigned int *edx);
- /* Unsafe MSR operations. These will warn or panic on failure. */
- u64 (*read_msr)(u32 msr);
- void (*write_msr)(u32 msr, u64 val);
-
- /*
- * Safe MSR operations.
- * Returns 0 or -EIO.
- */
- int (*read_msr_safe)(u32 msr, u64 *val);
- int (*write_msr_safe)(u32 msr, u64 val);
-
- u64 (*read_pmc)(int counter);
-
void (*start_context_switch)(struct task_struct *prev);
void (*end_context_switch)(struct task_struct *next);
#endif
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 00b59d774389..739dbfd8aadf 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -110,11 +110,6 @@ struct paravirt_patch_template pv_ops = {
.cpu.read_cr0 = native_read_cr0,
.cpu.write_cr0 = native_write_cr0,
.cpu.write_cr4 = native_write_cr4,
- .cpu.read_msr = native_read_msr,
- .cpu.write_msr = native_write_msr,
- .cpu.read_msr_safe = native_read_msr_safe,
- .cpu.write_msr_safe = native_write_msr_safe,
- .cpu.read_pmc = native_read_pmc,
.cpu.load_tr_desc = native_load_tr_desc,
.cpu.set_ldt = native_set_ldt,
.cpu.load_gdt = native_load_gdt,
@@ -212,6 +207,15 @@ struct paravirt_patch_template pv_ops = {
};
#ifdef CONFIG_PARAVIRT_XXL
+struct pv_msr_ops pv_ops_msr = {
+ .read_msr = native_read_msr,
+ .write_msr = native_write_msr,
+ .read_msr_safe = native_read_msr_safe,
+ .write_msr_safe = native_write_msr_safe,
+ .read_pmc = native_read_pmc,
+};
+EXPORT_SYMBOL(pv_ops_msr);
+
NOKPROBE_SYMBOL(native_load_idt);
#endif
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 2c64b388f616..bf81e84ff261 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1360,11 +1360,6 @@ asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
pv_ops.cpu.read_cr0 = xen_read_cr0;
pv_ops.cpu.write_cr0 = xen_write_cr0;
pv_ops.cpu.write_cr4 = xen_write_cr4;
- pv_ops.cpu.read_msr = xen_read_msr;
- pv_ops.cpu.write_msr = xen_write_msr;
- pv_ops.cpu.read_msr_safe = xen_read_msr_safe;
- pv_ops.cpu.write_msr_safe = xen_write_msr_safe;
- pv_ops.cpu.read_pmc = xen_read_pmc;
pv_ops.cpu.load_tr_desc = paravirt_nop;
pv_ops.cpu.set_ldt = xen_set_ldt;
pv_ops.cpu.load_gdt = xen_load_gdt;
@@ -1385,6 +1380,12 @@ asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
pv_ops.cpu.start_context_switch = xen_start_context_switch;
pv_ops.cpu.end_context_switch = xen_end_context_switch;
+ pv_ops_msr.read_msr = xen_read_msr;
+ pv_ops_msr.write_msr = xen_write_msr;
+ pv_ops_msr.read_msr_safe = xen_read_msr_safe;
+ pv_ops_msr.write_msr_safe = xen_write_msr_safe;
+ pv_ops_msr.read_pmc = xen_read_pmc;
+
xen_init_irq_ops();
/*
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 10b18cf9c360..2c91fcff77f4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -525,6 +525,7 @@ static struct {
} pv_ops_tables[] = {
{ .name = "pv_ops", },
{ .name = "pv_ops_lock", },
+ { .name = "pv_ops_msr", },
{ .name = NULL, .idx_off = -1 }
};
--
2.54.0