From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: [PATCH] ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault() Date: Mon, 8 Sep 2014 22:29:27 +0200 Message-ID: <1410208167-32532-1-git-send-email-ard.biesheuvel@linaro.org> Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, peter.maydell@linaro.org, lersek@redhat.com, Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com, christoffer.dall@linaro.org Return-path: Received: from mail-wi0-f181.google.com ([209.85.212.181]:35104 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754122AbaIHUa1 (ORCPT ); Mon, 8 Sep 2014 16:30:27 -0400 Received: by mail-wi0-f181.google.com with SMTP id e4so3361826wiv.2 for ; Mon, 08 Sep 2014 13:30:26 -0700 (PDT) Sender: kvm-owner@vger.kernel.org List-ID: The ISS encoding for an exception from a Data Abort has a WnR bit[6] that indicates whether the Data Abort was caused by a read or a write instruction. While there are several fields in the encoding that are only valid if the ISV bit[24] is set, WnR is not one of them, so we can read it unconditionally. Signed-off-by: Ard Biesheuvel --- This fixes an issue I observed with UEFI running under QEMU/KVM using NOR flash emulation and the upcoming KVM_CAP_READONLY_MEM support, where NOR flash reads were mistaken for NOR flash writes, resulting in all read accesses to go through the MMIO emulation layer. arch/arm/include/asm/kvm_mmu.h | 5 +---- arch/arm64/include/asm/kvm_mmu.h | 5 +---- 2 files changed, 2 insertions(+), 8 deletions(-) diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index 5cc0b0f5f72f..fad5648980ad 100644 --- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -83,10 +83,7 @@ static inline bool kvm_is_write_fault(unsigned long hsr) unsigned long hsr_ec = hsr >> HSR_EC_SHIFT; if (hsr_ec == HSR_EC_IABT) return false; - else if ((hsr & HSR_ISV) && !(hsr & HSR_WNR)) - return false; - else - return true; + return hsr & HSR_WNR; } static inline void kvm_clean_pgd(pgd_t *pgd) diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 8e138c7c53ac..09fd9e4c13d8 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -100,10 +100,7 @@ static inline bool kvm_is_write_fault(unsigned long esr) if (esr_ec == ESR_EL2_EC_IABT) return false; - if ((esr & ESR_EL2_ISV) && !(esr & ESR_EL2_WNR)) - return false; - - return true; + return esr & ESR_EL2_WNR; } static inline void kvm_clean_pgd(pgd_t *pgd) {} -- 1.8.3.2 From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Mon, 8 Sep 2014 22:29:27 +0200 Subject: [PATCH] ARM/arm64: KVM: fix use of WnR bit in kvm_is_write_fault() Message-ID: <1410208167-32532-1-git-send-email-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The ISS encoding for an exception from a Data Abort has a WnR bit[6] that indicates whether the Data Abort was caused by a read or a write instruction. While there are several fields in the encoding that are only valid if the ISV bit[24] is set, WnR is not one of them, so we can read it unconditionally. Signed-off-by: Ard Biesheuvel --- This fixes an issue I observed with UEFI running under QEMU/KVM using NOR flash emulation and the upcoming KVM_CAP_READONLY_MEM support, where NOR flash reads were mistaken for NOR flash writes, resulting in all read accesses to go through the MMIO emulation layer. arch/arm/include/asm/kvm_mmu.h | 5 +---- arch/arm64/include/asm/kvm_mmu.h | 5 +---- 2 files changed, 2 insertions(+), 8 deletions(-) diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index 5cc0b0f5f72f..fad5648980ad 100644 --- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -83,10 +83,7 @@ static inline bool kvm_is_write_fault(unsigned long hsr) unsigned long hsr_ec = hsr >> HSR_EC_SHIFT; if (hsr_ec == HSR_EC_IABT) return false; - else if ((hsr & HSR_ISV) && !(hsr & HSR_WNR)) - return false; - else - return true; + return hsr & HSR_WNR; } static inline void kvm_clean_pgd(pgd_t *pgd) diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 8e138c7c53ac..09fd9e4c13d8 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -100,10 +100,7 @@ static inline bool kvm_is_write_fault(unsigned long esr) if (esr_ec == ESR_EL2_EC_IABT) return false; - if ((esr & ESR_EL2_ISV) && !(esr & ESR_EL2_WNR)) - return false; - - return true; + return esr & ESR_EL2_WNR; } static inline void kvm_clean_pgd(pgd_t *pgd) {} -- 1.8.3.2