Re: [PATCH v3 10/14] x86/xen/msr: Remove pmu_msr_{read,write}()

[Jürgen Groß <jgross@xxxxxxxx>]

On 25.04.25 10:34, Xin Li (Intel) wrote:
> 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@xxxxxxxxx>
> Suggested-by: Juergen Gross <jgross@xxxxxxxx>
> Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
> ---
>
> 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          | 30 ++++++------------------------
>   arch/x86/xen/xen-ops.h      |  3 +--
>   3 files changed, 15 insertions(+), 33 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..6bee83018694 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 +297,16 @@ 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);
> +               return 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);
> +               return xen_intel_pmu_emulate(msr, val, type, index, is_read);
>         else
Can you please remove the two "else" instances above? With directly returning
form the "if" clause they are no longer needed.

With that you can add my:

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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