Re: [Xen-devel] [PATCH 03/18] xen/arm: Avoid setting/clearing HCR_RW at every context switch

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Stefano,

On 2017/3/15 8:25, Stefano Stabellini wrote:
> On Mon, 13 Mar 2017, Wei Chen wrote:
>> The HCR_EL2 flags for 64-bit and 32-bit domains are different. But
>> when we initialized the HCR_EL2 for vcpu0 of Dom0 and all vcpus of
>> DomU in vcpu_initialise, we didn't know the domain's address size
>> information. We had to use compatible flags to initialize HCR_EL2,
>> and set HCR_RW for 64-bit domain or clear HCR_RW for 32-bit domain
>> at every context switch.
>>
>> But, after we added the HCR_EL2 to vcpu's context, this behaviour
>> seems a little fussy. We can update the HCR_RW bit in vcpu's context
>> as soon as we get the domain's address size to avoid setting/clearing
>> HCR_RW at every context switch.
>>
>> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
>> ---
>>  xen/arch/arm/arm64/domctl.c  | 6 ++++++
>>  xen/arch/arm/domain.c        | 5 +++++
>>  xen/arch/arm/domain_build.c  | 7 +++++++
>>  xen/arch/arm/p2m.c           | 5 -----
>>  xen/include/asm-arm/domain.h | 1 +
>>  5 files changed, 19 insertions(+), 5 deletions(-)
>>
>> diff --git a/xen/arch/arm/arm64/domctl.c b/xen/arch/arm/arm64/domctl.c
>> index 44e1e7b..ab8781f 100644
>> --- a/xen/arch/arm/arm64/domctl.c
>> +++ b/xen/arch/arm/arm64/domctl.c
>> @@ -14,6 +14,8 @@
>>
>>  static long switch_mode(struct domain *d, enum domain_type type)
>>  {
>> +    struct vcpu *v;
>> +
>>      if ( d == NULL )
>>          return -EINVAL;
>>      if ( d->tot_pages != 0 )
>> @@ -23,6 +25,10 @@ static long switch_mode(struct domain *d, enum 
>> domain_type type)
>>
>>      d->arch.type = type;
>>
>> +    if ( is_64bit_domain(d) )
>> +        for_each_vcpu(d, v)
>> +            vcpu_switch_to_aarch64_mode(v);
>> +
>>      return 0;
>>  }
>>
>> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
>> index 5d18bb0..69c2854 100644
>> --- a/xen/arch/arm/domain.c
>> +++ b/xen/arch/arm/domain.c
>> @@ -537,6 +537,11 @@ void vcpu_destroy(struct vcpu *v)
>>      free_xenheap_pages(v->arch.stack, STACK_ORDER);
>>  }
>>
>> +void vcpu_switch_to_aarch64_mode(struct vcpu *v)
>> +{
>> +    v->arch.hcr_el2 |= HCR_RW;
>> +}
>
> if possible, I would write it as a static inline function
>

I had tried to write it as a static inline function in asm/domain.h
But while the first source file (arm64/asm-offsets.c) include
xen/sched.h wanted to compile this inline function it could not find
'struct vcpu'. Because the xen/sched.h included the asm/domain.h
but defined the vcpu type later. Even though we had included the
xen/sched.h in asm/domain.h already.


>
>>  int arch_domain_create(struct domain *d, unsigned int domcr_flags,
>>                         struct xen_arch_domainconfig *config)
>>  {
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index de59e5f..3abacc0 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -2148,6 +2148,10 @@ int construct_dom0(struct domain *d)
>>          return -EINVAL;
>>      }
>>      d->arch.type = kinfo.type;
>> +
>> +    if ( is_64bit_domain(d) )
>> +        vcpu_switch_to_aarch64_mode(v);
>> +
>>  #endif
>>
>>      allocate_memory(d, &kinfo);
>> @@ -2240,6 +2244,9 @@ int construct_dom0(struct domain *d)
>>              printk("Failed to allocate dom0 vcpu %d on pcpu %d\n", i, cpu);
>>              break;
>>          }
>> +
>> +        if ( is_64bit_domain(d) )
>> +            vcpu_switch_to_aarch64_mode(d->vcpu[i]);
>>      }
>>
>>      return 0;
>> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
>> index c49bfa6..1cba0d0 100644
>> --- a/xen/arch/arm/p2m.c
>> +++ b/xen/arch/arm/p2m.c
>> @@ -136,11 +136,6 @@ void p2m_restore_state(struct vcpu *n)
>>      WRITE_SYSREG64(p2m->vttbr, VTTBR_EL2);
>>      isb();
>>
>> -    if ( is_32bit_domain(n->domain) )
>> -        n->arch.hcr_el2 &= ~HCR_RW;
>> -    else
>> -        n->arch.hcr_el2 |= HCR_RW;
>> -
>>      WRITE_SYSREG(n->arch.sctlr, SCTLR_EL1);
>>      isb();
>>
>> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
>> index 7b1dacc..68185e2 100644
>> --- a/xen/include/asm-arm/domain.h
>> +++ b/xen/include/asm-arm/domain.h
>> @@ -268,6 +268,7 @@ struct arch_vcpu
>>
>>  void vcpu_show_execution_state(struct vcpu *);
>>  void vcpu_show_registers(const struct vcpu *);
>> +void vcpu_switch_to_aarch64_mode(struct vcpu *);
>>
>>  unsigned int domain_max_vcpus(const struct domain *);
>>
>> --
>> 2.7.4
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> https://lists.xen.org/xen-devel
>>
>


-- 
Regards,
Wei Chen

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