On 16/03/18 16:22, Catalin Marinas wrote:
> On Wed, Mar 14, 2018 at 04:50:42PM +0000, Marc Zyngier wrote:
>> All our useful entry points into the hypervisor are starting by
>> saving x0 and x1 on the stack. Let's move those into the vectors
>> by introducing macros that annotate whether a vector is valid or
>> not, thus indicating whether we want to stash registers or not.
>>
>> The only drawback is that we now also stash registers for el2_error,
>> but this should never happen, and we pop them back right at the
>> start of the handling sequence.
>>
>> Signed-off-by: Marc Zyngier <[email protected]>
>> ---
>> arch/arm64/kvm/hyp/hyp-entry.S | 56
>> ++++++++++++++++++++++++------------------
>> 1 file changed, 32 insertions(+), 24 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
>> index f36464bd57c5..0f62b5f76aa5 100644
>> --- a/arch/arm64/kvm/hyp/hyp-entry.S
>> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
>> @@ -55,7 +55,6 @@ ENTRY(__vhe_hyp_call)
>> ENDPROC(__vhe_hyp_call)
>>
>> el1_sync: // Guest trapped into EL2
>> - stp x0, x1, [sp, #-16]!
>>
>> alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
>> mrs x1, esr_el2
>> @@ -137,18 +136,18 @@ alternative_else_nop_endif
>> b __guest_exit
>>
>> el1_irq:
>> - stp x0, x1, [sp, #-16]!
>> ldr x1, [sp, #16 + 8]
>> mov x0, #ARM_EXCEPTION_IRQ
>> b __guest_exit
>>
>> el1_error:
>> - stp x0, x1, [sp, #-16]!
>> ldr x1, [sp, #16 + 8]
>> mov x0, #ARM_EXCEPTION_EL1_SERROR
>> b __guest_exit
>>
>> el2_error:
>> + ldp x0, x1, [sp], #16
>> +
>
> Nitpick: you don't need a memory access here, just:
>
> add sp, sp, #16
>
> (unless el2_error has changed somewhere before this patch)
At this point in the series, I agree. But starting with patch 22, we
start messing with x0 if HARDEN_EL2_VECTORS is valid, meaning we really
need to restore it in order to preserve the guest state.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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