| From b6ae256afd32f96bec0117175b329d0dd617655e Mon Sep 17 00:00:00 2001 |
| From: Christoffer Dall <christoffer.dall@arm.com> |
| Date: Thu, 12 Dec 2019 20:50:55 +0100 |
| Subject: KVM: arm64: Only sign-extend MMIO up to register width |
| |
| From: Christoffer Dall <christoffer.dall@arm.com> |
| |
| 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 <christoffer.dall@arm.com> |
| Signed-off-by: Marc Zyngier <maz@kernel.org> |
| Cc: stable@vger.kernel.org |
| Link: https://lore.kernel.org/r/20191212195055.5541-1-christoffer.dall@arm.com |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm/include/asm/kvm_emulate.h | 5 +++++ |
| arch/arm/include/asm/kvm_mmio.h | 2 ++ |
| arch/arm64/include/asm/kvm_emulate.h | 5 +++++ |
| arch/arm64/include/asm/kvm_mmio.h | 6 ++---- |
| virt/kvm/arm/mmio.c | 6 ++++++ |
| 5 files changed, 20 insertions(+), 4 deletions(-) |
| |
| --- a/arch/arm/include/asm/kvm_emulate.h |
| +++ b/arch/arm/include/asm/kvm_emulate.h |
| @@ -206,6 +206,11 @@ static inline bool kvm_vcpu_dabt_issext( |
| 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; |
| --- 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; |
| }; |
| |
| void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data); |
| --- a/arch/arm64/include/asm/kvm_emulate.h |
| +++ b/arch/arm64/include/asm/kvm_emulate.h |
| @@ -293,6 +293,11 @@ static inline bool kvm_vcpu_dabt_issext( |
| return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SSE); |
| } |
| |
| +static inline bool kvm_vcpu_dabt_issf(const struct kvm_vcpu *vcpu) |
| +{ |
| + return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SF); |
| +} |
| + |
| static inline int kvm_vcpu_dabt_get_rd(const struct kvm_vcpu *vcpu) |
| { |
| return (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT; |
| --- a/arch/arm64/include/asm/kvm_mmio.h |
| +++ b/arch/arm64/include/asm/kvm_mmio.h |
| @@ -21,13 +21,11 @@ |
| #include <linux/kvm_host.h> |
| #include <asm/kvm_arm.h> |
| |
| -/* |
| - * 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; |
| }; |
| |
| void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data); |
| --- a/virt/kvm/arm/mmio.c |
| +++ b/virt/kvm/arm/mmio.c |
| @@ -117,6 +117,9 @@ int kvm_handle_mmio_return(struct kvm_vc |
| 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); |
| @@ -137,6 +140,7 @@ static int decode_hsr(struct kvm_vcpu *v |
| unsigned long rt; |
| int access_size; |
| bool sign_extend; |
| + bool sixty_four; |
| |
| if (kvm_vcpu_dabt_iss1tw(vcpu)) { |
| /* page table accesses IO mem: tell guest to fix its TTBR */ |
| @@ -150,11 +154,13 @@ static int decode_hsr(struct kvm_vcpu *v |
| |
| *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); |
| |
| *len = access_size; |
| vcpu->arch.mmio_decode.sign_extend = sign_extend; |
| vcpu->arch.mmio_decode.rt = rt; |
| + vcpu->arch.mmio_decode.sixty_four = sixty_four; |
| |
| return 0; |
| } |