Re: [Xen-devel] [PATCH v3 03/38] arm/p2m: Introduce p2m_(switch|restore)_vttbr_and_(g|s)et_flags

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

Hi Julien,

On 09/01/2016 05:51 PM, Julien Grall wrote:
> Hello Sergej,
> 
> On 16/08/16 23:16, Sergej Proskurin wrote:
>> This commit introduces macros for switching and restoring the vttbr
>> considering the currently set irq flags. We define these macros, as the
>> following commits will use the associated functionality multiple times
>> throughout the file ./xen/arch/arm/p2m.c.
>>
>> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
>> ---
>> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> Cc: Julien Grall <julien.grall@xxxxxxx>
>> ---
>>  xen/arch/arm/p2m.c | 37 +++++++++++++++++++++++--------------
>>  1 file changed, 23 insertions(+), 14 deletions(-)
>>
>> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
>> index 08114d8..02e9ee7 100644
>> --- a/xen/arch/arm/p2m.c
>> +++ b/xen/arch/arm/p2m.c
>> @@ -27,6 +27,26 @@ static unsigned int __read_mostly p2m_root_level;
>>
>>  #define P2M_ROOT_PAGES    (1<<P2M_ROOT_ORDER)
>>
>> +#define p2m_switch_vttbr_and_get_flags(ovttbr, nvttbr, flags)       \
>> +({                                                                  \
> 
> It makes more sense to save the content of VTTBR_EL2 in the macro.
> 

I assume you mean the VTTBR_EL2 within the macro parameter ovttbr. I
will move the definition of the ovttbr variable into the macro and
return its value at the end so that it can be subsequently provided with
the "p2m_restore_vttbr_and_set_flags" macro. Thank you.

>> +    if ( ovttbr != nvttbr )                                         \
>> +    {                                                               \
>> +        local_irq_save(flags);                                      \
>> +        WRITE_SYSREG64(nvttbr, VTTBR_EL2);                          \
>> +        isb();                                                      \
>> +    }                                                               \
>> +})
>> +
>> +#define p2m_restore_vttbr_and_set_flags(ovttbr, flags)              \
>> +({                                                                  \
>> +    if ( ovttbr != READ_SYSREG64(VTTBR_EL2) )                       \
>> +    {                                                               \
>> +        WRITE_SYSREG64(ovttbr, VTTBR_EL2);                          \
>> +        isb();                                                      \
>> +        local_irq_restore(flags);                                   \
>> +    }                                                               \
>> +})
>> +
>>  unsigned int __read_mostly p2m_ipa_bits;
>>
>>  /* Helpers to lookup the properties of each level */
>> @@ -173,28 +193,17 @@ void p2m_restore_state(struct vcpu *n)
>>  static void p2m_flush_tlb(struct p2m_domain *p2m)
>>  {
>>      unsigned long flags = 0;
>> -    uint64_t ovttbr;
>> +    uint64_t ovttbr = READ_SYSREG64(VTTBR_EL2);
>>
>>      /*
>>       * ARM only provides an instruction to flush TLBs for the current
>>       * VMID. So switch to the VTTBR of a given P2M if different.
>>       */
>> -    ovttbr = READ_SYSREG64(VTTBR_EL2);
>> -    if ( ovttbr != p2m->vttbr )
>> -    {
>> -        local_irq_save(flags);
>> -        WRITE_SYSREG64(p2m->vttbr, VTTBR_EL2);
>> -        isb();
>> -    }
>> +    p2m_switch_vttbr_and_get_flags(ovttbr, p2m->vttbr, flags);
>>
>>      flush_tlb();
>>
>> -    if ( ovttbr != READ_SYSREG64(VTTBR_EL2) )
>> -    {
>> -        WRITE_SYSREG64(ovttbr, VTTBR_EL2);
>> -        isb();
>> -        local_irq_restore(flags);
>> -    }
>> +    p2m_restore_vttbr_and_set_flags(ovttbr, flags);
>>  }
>>
>>  /*
>>
> 
> Regards,
> 


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