Re: [PATCH 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap
From: Mark Rutland <mark.rutland@arm.com>
Date: 2020-10-26 13:55:15
Also in:
kvm, kvmarm
On Mon, Oct 26, 2020 at 01:34:40PM +0000, Marc Zyngier wrote:
On SMC trap, the prefered return address is set to that of the SMC instruction itself. It is thus wrong to tyr and roll it back when
Typo: s/tyr/try/
an SError occurs while trapping on SMC. It is still necessary on HVC though, as HVC doesn't cause a trap, and sets ELR to returning *after* the HVC. It also became apparent that the is 16bit encoding for an AArch32
I guess s/that the is/that there is no/ ?
HVC instruction, meaning that the displacement is always 4 bytes, no matter what the ISA is. Take this opportunity to simplify it. Signed-off-by: Marc Zyngier <maz@kernel.org>
Assuming that there is no 16-bit HVC: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark.
quoted hunk ↗ jump to hunk
--- arch/arm64/kvm/handle_exit.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 5d690d60ccad..79a720657c47 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c@@ -245,15 +245,15 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index) u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu)); /* - * HVC/SMC already have an adjusted PC, which we need - * to correct in order to return to after having - * injected the SError. + * HVC already have an adjusted PC, which we need to + * correct in order to return to after having injected + * the SError. + * + * SMC, on the other hand, is *trapped*, meaning its + * preferred return address is the SMC itself. */ - if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64 || - esr_ec == ESR_ELx_EC_SMC32 || esr_ec == ESR_ELx_EC_SMC64) { - u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2; - *vcpu_pc(vcpu) -= adj; - } + if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64) + *vcpu_pc(vcpu) -= 4; return 1; }-- 2.28.0 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
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