Re: [Xen-devel] [PATCH v4 1/5] x86/paravirt: Add _safe to the read_msr and write_msr PV hooks

[Andy Lutomirski <luto@xxxxxxxxxxxxxx>]

On Mon, Mar 14, 2016 at 4:57 AM, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Sat, Mar 12, 2016 at 10:08:48AM -0800, Andy Lutomirski wrote:
>> These hooks match the _safe variants, so name them accordingly.
>> This will make room for unsafe PV hooks.
>>
>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
>> ---
>>  arch/x86/include/asm/paravirt.h       | 33 +++++++++++++++++----------------
>>  arch/x86/include/asm/paravirt_types.h |  8 ++++----
>>  arch/x86/kernel/paravirt.c            |  4 ++--
>>  arch/x86/xen/enlighten.c              |  4 ++--
>>  4 files changed, 25 insertions(+), 24 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/paravirt.h 
>> b/arch/x86/include/asm/paravirt.h
>> index f6192502149e..2e49228ed9a3 100644
>> --- a/arch/x86/include/asm/paravirt.h
>> +++ b/arch/x86/include/asm/paravirt.h
>> @@ -129,34 +129,35 @@ static inline void wbinvd(void)
>>
>>  #define get_kernel_rpl()  (pv_info.kernel_rpl)
>>
>> -static inline u64 paravirt_read_msr(unsigned msr, int *err)
>> +static inline u64 paravirt_read_msr_safe(unsigned msr, int *err)
>>  {
>> -     return PVOP_CALL2(u64, pv_cpu_ops.read_msr, msr, err);
>> +     return PVOP_CALL2(u64, pv_cpu_ops.read_msr_safe, msr, err);
>>  }
>>
>> -static inline int paravirt_write_msr(unsigned msr, unsigned low, unsigned 
>> high)
>> +static inline int paravirt_write_msr_safe(unsigned msr,
>> +                                       unsigned low, unsigned high)
>>  {
>> -     return PVOP_CALL3(int, pv_cpu_ops.write_msr, msr, low, high);
>> +     return PVOP_CALL3(int, pv_cpu_ops.write_msr_safe, msr, low, high);
>>  }
>>
>>  /* These should all do BUG_ON(_err), but our headers are too tangled. */
>>  #define rdmsr(msr, val1, val2)                       \
>>  do {                                         \
>>       int _err;                               \
>> -     u64 _l = paravirt_read_msr(msr, &_err); \
>> +     u64 _l = paravirt_read_msr_safe(msr, &_err);    \
>>       val1 = (u32)_l;                         \
>>       val2 = _l >> 32;                        \
>>  } while (0)
>>
>>  #define wrmsr(msr, val1, val2)                       \
>>  do {                                         \
>> -     paravirt_write_msr(msr, val1, val2);    \
>> +     paravirt_write_msr_safe(msr, val1, val2);       \
>>  } while (0)
>>
>>  #define rdmsrl(msr, val)                     \
>>  do {                                         \
>>       int _err;                               \
>> -     val = paravirt_read_msr(msr, &_err);    \
>> +     val = paravirt_read_msr_safe(msr, &_err);       \
>>  } while (0)
>>
>>  static inline void wrmsrl(unsigned msr, u64 val)
>> @@ -164,23 +165,23 @@ static inline void wrmsrl(unsigned msr, u64 val)
>>       wrmsr(msr, (u32)val, (u32)(val>>32));
>>  }
>>
>> -#define wrmsr_safe(msr, a, b)        paravirt_write_msr(msr, a, b)
>> +#define wrmsr_safe(msr, a, b)        paravirt_write_msr_safe(msr, a, b)
>>
>>  /* rdmsr with exception handling */
>> -#define rdmsr_safe(msr, a, b)                        \
>> -({                                           \
>> -     int _err;                               \
>> -     u64 _l = paravirt_read_msr(msr, &_err); \
>> -     (*a) = (u32)_l;                         \
>> -     (*b) = _l >> 32;                        \
>> -     _err;                                   \
>> +#define rdmsr_safe(msr, a, b)                                \
>> +({                                                   \
>> +     int _err;                                       \
>> +     u64 _l = paravirt_read_msr_safe(msr, &_err);    \
>> +     (*a) = (u32)_l;                                 \
>> +     (*b) = _l >> 32;                                \
>> +     _err;                                           \
>>  })
>>
>>  static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
>>  {
>>       int err;
>>
>> -     *p = paravirt_read_msr(msr, &err);
>> +     *p = paravirt_read_msr_safe(msr, &err);
>>       return err;
>>  }
>>
>> diff --git a/arch/x86/include/asm/paravirt_types.h 
>> b/arch/x86/include/asm/paravirt_types.h
>> index 77db5616a473..5a06cccd36f0 100644
>> --- a/arch/x86/include/asm/paravirt_types.h
>> +++ b/arch/x86/include/asm/paravirt_types.h
>> @@ -155,10 +155,10 @@ struct pv_cpu_ops {
>>       void (*cpuid)(unsigned int *eax, unsigned int *ebx,
>>                     unsigned int *ecx, unsigned int *edx);
>>
>> -     /* MSR, PMC and TSR operations.
>> -        err = 0/-EFAULT.  wrmsr returns 0/-EFAULT. */
>> -     u64 (*read_msr)(unsigned int msr, int *err);
>> -     int (*write_msr)(unsigned int msr, unsigned low, unsigned high);
>> +     /* MSR operations.
>> +        err = 0/-EIO.  wrmsr returns 0/-EIO. */
>
> Please fix the comment format while you're touching this :
>
>         /*
>          * A sentence.
>          * Another sentence.
>          */
>
> Other than that:
>
> Acked-by: Borislav Petkov <bp@xxxxxxx>

I fixed this in "x86/paravirt: Add paravirt_{read,write}_msr" later in
the series.  Is that good enough?

--Andy

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