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From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>
Subject: [PATCH 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap
Date: Mon, 26 Oct 2020 13:34:40 +0000	[thread overview]
Message-ID: <20201026133450.73304-2-maz@kernel.org> (raw)
In-Reply-To: <20201026133450.73304-1-maz@kernel.org>

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
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
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>
---
 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

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  reply	other threads:[~2020-10-26 13:35 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 ` Marc Zyngier [this message]
2020-10-26 13:53   ` [PATCH 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap 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
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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