From: James Morse <james.morse@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Andrew Scull <ascull@google.com>, Will Deacon <will@kernel.org>,
Quentin Perret <qperret@google.com>,
David Brazdil <dbrazdil@google.com>,
kernel-team@android.com
Subject: Re: [PATCH 04/11] KVM: arm64: Move PC rollback on SError to HYP
Date: Tue, 27 Oct 2020 14:56:05 +0000 [thread overview]
Message-ID: <e2487f06-3f2f-1a0b-49d8-a72ea9288bb2@arm.com> (raw)
In-Reply-To: <20201026133450.73304-5-maz@kernel.org>
Hi Marc,
On 26/10/2020 13:34, Marc Zyngier wrote:
> Instead of handling the "PC rollback on SError during HVC" at EL1 (which
> requires disclosing PC to a potentially untrusted kernel), let's move
> this fixup to ... fixup_guest_exit(), which is where we do all fixups.
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index d687e574cde5..668f02c7b0b3 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -411,6 +411,21 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
> if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
> vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
>
> + if (ARM_SERROR_PENDING(*exit_code)) {
> + u8 esr_ec = kvm_vcpu_trap_get_class(vcpu);
> +
> + /*
> + * 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)
> + *vcpu_pc(vcpu) -= 4;
Isn't *vcpu_pc(vcpu) the PC of the previous entry for this vcpu?.... its not the PC of the
exit until __sysreg_save_el2_return_state() saves it, which happens just after
fixup_guest_exit().
Mess with ELR_EL2 directly?
Thanks,
James
> + }
> +
> /*
> * We're using the raw exception code in order to only process
> * the trap if no SError is pending. We will come back to the
>
next prev parent reply other threads:[~2020-10-27 14:56 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 13:34 [PATCH 00/11] KVM: arm64: Move PC/ELR/SPSR/PSTATE updatess to EL2 Marc Zyngier
2020-10-26 13:34 ` [PATCH 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap Marc Zyngier
2020-10-26 13:53 ` Mark Rutland
2020-10-26 14:08 ` Marc Zyngier
2020-10-26 14:22 ` Mark Rutland
2020-10-26 13:34 ` [PATCH 02/11] KVM: arm64: Move kvm_vcpu_trap_il_is32bit into kvm_skip_instr32() Marc Zyngier
2020-10-26 13:55 ` Mark Rutland
2020-10-26 13:34 ` [PATCH 03/11] KVM: arm64: Make kvm_skip_instr() and co private to HYP Marc Zyngier
2020-10-26 14:04 ` Mark Rutland
2020-10-27 16:17 ` Marc Zyngier
2020-10-27 10:55 ` Suzuki K Poulose
2020-10-27 11:08 ` Marc Zyngier
2020-10-26 13:34 ` [PATCH 04/11] KVM: arm64: Move PC rollback on SError " Marc Zyngier
2020-10-26 14:06 ` Mark Rutland
2020-10-27 14:56 ` James Morse [this message]
2020-10-27 14:59 ` Marc Zyngier
2020-10-26 13:34 ` [PATCH 05/11] KVM: arm64: Move VHE direct sysreg accessors into kvm_host.h Marc Zyngier
2020-10-26 14:07 ` Mark Rutland
2020-10-26 13:34 ` [PATCH 06/11] KVM: arm64: Add basic hooks for injecting exceptions from EL2 Marc Zyngier
2020-10-26 13:34 ` [PATCH 07/11] KVM: arm64: Inject AArch64 exceptions from HYP Marc Zyngier
2020-10-26 14:22 ` Mark Rutland
2020-10-27 16:21 ` Marc Zyngier
2020-10-27 17:41 ` James Morse
2020-10-27 18:49 ` Marc Zyngier
2020-10-26 13:34 ` [PATCH 08/11] KVM: arm64: Inject AArch32 " Marc Zyngier
2020-10-26 14:26 ` Mark Rutland
2020-10-27 17:41 ` James Morse
2020-10-27 19:21 ` Marc Zyngier
2020-10-28 19:20 ` James Morse
2020-10-28 20:24 ` Marc Zyngier
2020-10-26 13:34 ` [PATCH 09/11] KVM: arm64: Remove SPSR manipulation primitives Marc Zyngier
2020-10-26 14:30 ` Mark Rutland
2020-10-26 13:34 ` [PATCH 10/11] KVM: arm64: Consolidate exception injection Marc Zyngier
2020-10-26 13:34 ` [PATCH 11/11] KVM: arm64: Get rid of the AArch32 register mapping code Marc Zyngier
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