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From: Mark Rutland <mark.rutland@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>,
	kernel-team@android.com, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org
Subject: Re: [PATCH 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap
Date: Mon, 26 Oct 2020 13:53:08 +0000	[thread overview]
Message-ID: <20201026135308.GC12454@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20201026133450.73304-2-maz@kernel.org>

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.

> ---
>  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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  reply	other threads:[~2020-10-26 13:53 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 [this message]
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
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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