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 <marc.zyngier@xxxxxxx> >> --- >> 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...
