[PATCH v4 11/15] x86/xen/msr: Remove pmu_msr_{read,write}()

Xin Li (Intel)
2025-04-27T09:21:35Z

As pmu_msr_{read,write}() are now wrappers of pmu_msr_chk_emulated(),
remove them and use pmu_msr_chk_emulated() directly.

As pmu_msr_chk_emulated() could easily return false in the cases where
it would set *emul to false, remove the "emul" argument and use the
return value instead.

While at it, convert the data type of MSR index to u32 in functions
called in pmu_msr_chk_emulated().

Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Suggested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---

Change in v4:
*) Remove two "else" that no longer make sense (Juergen Gross).

Change in v3:
*) Remove the "emul" argument of pmu_msr_chk_emulated() (Juergen Gross).
---
arch/x86/xen/enlighten_pv.c | 15 ++++++++-------
arch/x86/xen/pmu.c | 33 ++++++++-------------------------
arch/x86/xen/xen-ops.h | 3 +--
3 files changed, 17 insertions(+), 34 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 61e51a970f3c..528a2f4df050 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1090,7 +1090,7 @@ static u64 xen_do_read_msr(unsigned int msr, int *err)
{
u64 val = 0; /* Avoid uninitialized value for safe variant. */

- if (pmu_msr_read_emulated(msr, &val))
+ if (pmu_msr_chk_emulated(msr, &val, true))
return val;

if (err)
@@ -1162,12 +1162,13 @@ static void xen_do_write_msr(unsigned int msr, unsigned int low,
default:
val = (u64)high << 32 | low;

- if (!pmu_msr_write_emulated(msr, val)) {
- if (err)
- *err = native_write_msr_safe(msr, low, high);
- else
- native_write_msr(msr, low, high);
- }
+ if (pmu_msr_chk_emulated(msr, &val, false))
+ return;
+
+ if (err)
+ *err = native_write_msr_safe(msr, low, high);
+ else
+ native_write_msr(msr, low, high);
}
}

diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index b6557f2d1a2e..5f3d2a6c70f1 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -128,7 +128,7 @@ static inline uint32_t get_fam15h_addr(u32 addr)
return addr;
}

-static inline bool is_amd_pmu_msr(unsigned int msr)
+static bool is_amd_pmu_msr(u32 msr)
{
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
@@ -194,8 +194,7 @@ static bool is_intel_pmu_msr(u32 msr_index, int *type, int *index)
}
}

-static bool xen_intel_pmu_emulate(unsigned int msr, u64 *val, int type,
- int index, bool is_read)
+static bool xen_intel_pmu_emulate(u32 msr, u64 *val, int type, int index, bool is_read)
{
uint64_t *reg = NULL;
struct xen_pmu_intel_ctxt *ctxt;
@@ -257,7 +256,7 @@ static bool xen_intel_pmu_emulate(unsigned int msr, u64 *val, int type,
return false;
}

-static bool xen_amd_pmu_emulate(unsigned int msr, u64 *val, bool is_read)
+static bool xen_amd_pmu_emulate(u32 msr, u64 *val, bool is_read)
{
uint64_t *reg = NULL;
int i, off = 0;
@@ -298,33 +297,17 @@ static bool xen_amd_pmu_emulate(unsigned int msr, u64 *val, bool is_read)
return false;
}

-static bool pmu_msr_chk_emulated(unsigned int msr, uint64_t *val, bool is_read,
- bool *emul)
+bool pmu_msr_chk_emulated(u32 msr, u64 *val, bool is_read)
{
int type, index = 0;

if (is_amd_pmu_msr(msr))
- *emul = xen_amd_pmu_emulate(msr, val, is_read);
- else if (is_intel_pmu_msr(msr, &type, &index))
- *emul = xen_intel_pmu_emulate(msr, val, type, index, is_read);
- else
- return false;
-
- return true;
-}
-
-bool pmu_msr_read_emulated(u32 msr, u64 *val)
-{
- bool emulated;
+ return xen_amd_pmu_emulate(msr, val, is_read);

- return pmu_msr_chk_emulated(msr, val, true, &emulated) && emulated;
-}
+ if (is_intel_pmu_msr(msr, &type, &index))
+ return xen_intel_pmu_emulate(msr, val, type, index, is_read);

-bool pmu_msr_write_emulated(u32 msr, u64 val)
-{
- bool emulated;
-
- return pmu_msr_chk_emulated(msr, &val, false, &emulated) && emulated;
+ return false;
}

static u64 xen_amd_read_pmc(int counter)
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 163e03e33089..fd7f845b83a3 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -274,8 +274,7 @@ void xen_pmu_finish(int cpu);
static inline void xen_pmu_init(int cpu) {}
static inline void xen_pmu_finish(int cpu) {}
#endif
-bool pmu_msr_read_emulated(u32 msr, u64 *val);
-bool pmu_msr_write_emulated(u32 msr, u64 val);
+bool pmu_msr_chk_emulated(u32 msr, u64 *val, bool is_read);
int pmu_apic_update(uint32_t reg);
u64 xen_read_pmc(int counter);

--
2.49.0