From 6a73af05d634d774f72ea41f9518c777743726bc Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Thu, 12 Dec 2019 20:50:55 +0100 Subject: KVM: arm64: Only sign-extend MMIO up to register width commit b6ae256afd32f96bec0117175b329d0dd617655e upstream. On AArch64 you can do a sign-extended load to either a 32-bit or 64-bit register, and we should only sign extend the register up to the width of the register as specified in the operation (by using the 32-bit Wn or 64-bit Xn register specifier). As it turns out, the architecture provides this decoding information in the SF ("Sixty-Four" -- how cute...) bit. Let's take advantage of this with the usual 32-bit/64-bit header file dance and do the right thing on AArch64 hosts. Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20191212195055.5541-1-christoffer.dall@arm.com [bwh: Backported to 3.16: - Use ESR_EL2_SF - Adjust filename, context] Signed-off-by: Ben Hutchings --- arch/arm/include/asm/kvm_emulate.h | 5 +++++ arch/arm/include/asm/kvm_mmio.h | 2 ++ arch/arm/kvm/mmio.c | 6 ++++++ arch/arm64/include/asm/kvm_emulate.h | 5 +++++ arch/arm64/include/asm/kvm_mmio.h | 6 ++---- 5 files changed, 20 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h index 853e2becad18..8d704db1ce96 100644 --- a/arch/arm/include/asm/kvm_emulate.h +++ b/arch/arm/include/asm/kvm_emulate.h @@ -105,6 +105,11 @@ static inline bool kvm_vcpu_dabt_issext(struct kvm_vcpu *vcpu) return kvm_vcpu_get_hsr(vcpu) & HSR_SSE; } +static inline bool kvm_vcpu_dabt_issf(const struct kvm_vcpu *vcpu) +{ + return false; +} + static inline int kvm_vcpu_dabt_get_rd(struct kvm_vcpu *vcpu) { return (kvm_vcpu_get_hsr(vcpu) & HSR_SRT_MASK) >> HSR_SRT_SHIFT; diff --git a/arch/arm/include/asm/kvm_mmio.h b/arch/arm/include/asm/kvm_mmio.h index adcc0d7d3175..e28cef4beae8 100644 --- a/arch/arm/include/asm/kvm_mmio.h +++ b/arch/arm/include/asm/kvm_mmio.h @@ -26,6 +26,8 @@ struct kvm_decode { unsigned long rt; bool sign_extend; + /* Not used on 32-bit arm */ + bool sixty_four; }; /* diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c index c47f108c2b8a..c480bd438fd0 100644 --- a/arch/arm/kvm/mmio.c +++ b/arch/arm/kvm/mmio.c @@ -112,6 +112,9 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) data = (data ^ mask) - mask; } + if (!vcpu->arch.mmio_decode.sixty_four) + data = data & 0xffffffff; + trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr, &data); data = vcpu_data_host_to_guest(vcpu, data, len); @@ -127,6 +130,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, unsigned long rt; int len; bool is_write, sign_extend; + bool sixty_four; if (kvm_vcpu_dabt_isextabt(vcpu)) { /* cache operation on I/O addr, tell guest unsupported */ @@ -146,6 +150,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, is_write = kvm_vcpu_dabt_iswrite(vcpu); sign_extend = kvm_vcpu_dabt_issext(vcpu); + sixty_four = kvm_vcpu_dabt_issf(vcpu); rt = kvm_vcpu_dabt_get_rd(vcpu); mmio->is_write = is_write; @@ -153,6 +158,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, mmio->len = len; vcpu->arch.mmio_decode.sign_extend = sign_extend; vcpu->arch.mmio_decode.rt = rt; + vcpu->arch.mmio_decode.sixty_four = sixty_four; /* * The MMIO instruction is emulated and should not be re-executed diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index ef490a55cdf1..9e1f3250bd73 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -140,6 +140,11 @@ static inline bool kvm_vcpu_dabt_issext(const struct kvm_vcpu *vcpu) return !!(kvm_vcpu_get_hsr(vcpu) & ESR_EL2_SSE); } +static inline bool kvm_vcpu_dabt_issf(const struct kvm_vcpu *vcpu) +{ + return !!(kvm_vcpu_get_hsr(vcpu) & ESR_EL2_SF); +} + static inline int kvm_vcpu_dabt_get_rd(const struct kvm_vcpu *vcpu) { return (kvm_vcpu_get_hsr(vcpu) & ESR_EL2_SRT_MASK) >> ESR_EL2_SRT_SHIFT; diff --git a/arch/arm64/include/asm/kvm_mmio.h b/arch/arm64/include/asm/kvm_mmio.h index fc2f689c0694..09923122c4c9 100644 --- a/arch/arm64/include/asm/kvm_mmio.h +++ b/arch/arm64/include/asm/kvm_mmio.h @@ -22,13 +22,11 @@ #include #include -/* - * This is annoying. The mmio code requires this, even if we don't - * need any decoding. To be fixed. - */ struct kvm_decode { unsigned long rt; bool sign_extend; + /* Witdth of the register accessed by the faulting instruction is 64-bits */ + bool sixty_four; }; /* -- cgit v1.2.3