Hi Stefano,
On 01/10/2019 23:19, Stefano Stabellini wrote:
> On Thu, 26 Sep 2019, Julien Grall wrote:
>> Using alternative_if makes the code a bit more streamlined.
>>
>> Take the opportunity to use the new auto-nop infrastructure to avoid
>> counting the number of nop in the else part for arch/arm/arm64/entry.S
>>
>> Signed-off-by: Julien Grall <julien.gr...@arm.com>
>>
>> ---
>> This is pretty much a matter of taste, but at least for arm64 this
>> allows us to use the auto-nop infrastructure. So the arm32 is more
>> to keep inline with arm64.
>> ---
>> xen/arch/arm/arm32/entry.S | 9 ++++++---
>> xen/arch/arm/arm64/entry.S | 8 +++++---
>> 2 files changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S
>> index 0b4cd19abd..1428cd3583 100644
>> --- a/xen/arch/arm/arm32/entry.S
>> +++ b/xen/arch/arm/arm32/entry.S
>> @@ -65,9 +65,12 @@ save_guest_regs:
>> * If the SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT has been set in the
>> cpu
>> * feature, the checking of pending SErrors will be skipped.
>> */
>> - ALTERNATIVE("nop",
>> - "b skip_check",
>> - SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
>> + alternative_if SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT
>> + nop
>> + alternative_else
>> + b skip_check
>> + alternative_endif
>
> This could be written as:
>
> alternative_if_not SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT
> b skip_check
> alternative_else_nop_endif
Actually my implementation is wrong :/. We want to skip the check if the
cap is set. So this should be:
alternative_if SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT
b skip_check
alternative_else_nop_endif
>
>
>> /*
>> * Start to check pending virtual abort in the gap of Guest -> HYP
>> * world switch.
>> diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S
>> index 458d12f188..91cf6ee6f4 100644
>> --- a/xen/arch/arm/arm64/entry.S
>> +++ b/xen/arch/arm/arm64/entry.S
>> @@ -170,9 +170,11 @@
>> * is not set. If a vSError took place, the initial exception will
>> be
>> * skipped. Exit ASAP
>> */
>> - ALTERNATIVE("bl check_pending_vserror; cbnz x0, 1f",
>> - "nop; nop",
>> - SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
>> + alternative_if SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT
This would need to be alternative_if_not as want to call the function
when the cap is not set.
>> + bl check_pending_vserror
>> + cbnz x0, 1f
>> + alternative_else_nop_endif
>> +
>> mov x0, sp
>> bl enter_hypervisor_from_guest_noirq
>> msr daifclr, \iflags
>> --
>> 2.11.0
>>
Cheeers,
--
Julien Grall
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