| Message ID | 20240226100601.2379693-13-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM/arm64: Add NV support for ERET and PAuth | expand |
On Mon, Feb 26, 2024 at 10:06:00AM +0000, Marc Zyngier wrote: > Now that we have some emulation in place for ERETA[AB], we can > plug it into the exception handling machinery. > > As for a bare ERET, an "easy" ERETAx instruction is processed as > a fixup, while something that requires a translation regime > transition or an exception delivery is left to the slow path. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > arch/arm64/kvm/emulate-nested.c | 22 ++++++++++++++++++++-- > arch/arm64/kvm/handle_exit.c | 3 ++- > arch/arm64/kvm/hyp/vhe/switch.c | 13 +++++++++++-- > 3 files changed, 33 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c > index 63a74c0330f1..72d733c74a38 100644 > --- a/arch/arm64/kvm/emulate-nested.c > +++ b/arch/arm64/kvm/emulate-nested.c > @@ -2172,7 +2172,7 @@ static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr) > > void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) > { > - u64 spsr, elr; > + u64 spsr, elr, esr; > > /* > * Forward this trap to the virtual EL2 if the virtual > @@ -2181,12 +2181,30 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) > if (forward_traps(vcpu, HCR_NV)) > return; > > + /* Check for an ERETAx */ > + esr = kvm_vcpu_get_esr(vcpu); > + if (esr_iss_is_eretax(esr) && !kvm_auth_eretax(vcpu, &elr)) { > + /* > + * Oh no, ERETAx failed to authenticate. If we have > + * FPACCOMBINE, deliver an exception right away. If we > + * don't, then let the mangled ELR value trickle down the > + * ERET handling, and the guest will have a little surprise. > + */ > + if (kvm_has_pauth(vcpu->kvm, FPACCOMBINE)) { > + esr &= ESR_ELx_ERET_ISS_ERETA; > + esr |= FIELD_PREP(ESR_ELx_EC_MASK, ESR_ELx_EC_FPAC); > + kvm_inject_nested_sync(vcpu, esr); > + return; > + } > + } > + > preempt_disable(); > kvm_arch_vcpu_put(vcpu); > > spsr = __vcpu_sys_reg(vcpu, SPSR_EL2); > spsr = kvm_check_illegal_exception_return(vcpu, spsr); > - elr = __vcpu_sys_reg(vcpu, ELR_EL2); > + if (!esr_iss_is_eretax(esr)) > + elr = __vcpu_sys_reg(vcpu, ELR_EL2); > > trace_kvm_nested_eret(vcpu, elr, spsr); > > diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c > index 1ba2f788b2c3..407bdfbb572b 100644 > --- a/arch/arm64/kvm/handle_exit.c > +++ b/arch/arm64/kvm/handle_exit.c > @@ -248,7 +248,8 @@ static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) > > static int kvm_handle_eret(struct kvm_vcpu *vcpu) > { > - if (esr_iss_is_eretax(kvm_vcpu_get_esr(vcpu))) > + if (esr_iss_is_eretax(kvm_vcpu_get_esr(vcpu)) && > + !vcpu_has_ptrauth(vcpu)) > return kvm_handle_ptrauth(vcpu); > > /* > diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c > index 3ea9bdf6b555..49d36666040e 100644 > --- a/arch/arm64/kvm/hyp/vhe/switch.c > +++ b/arch/arm64/kvm/hyp/vhe/switch.c > @@ -208,7 +208,8 @@ void kvm_vcpu_put_vhe(struct kvm_vcpu *vcpu) > > static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) > { > - u64 spsr, mode; > + u64 esr = kvm_vcpu_get_esr(vcpu); > + u64 spsr, elr, mode; > > /* > * Going through the whole put/load motions is a waste of time > @@ -242,10 +243,18 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) > return false; > } > > + /* If ERETAx fails, take the slow path */ > + if (esr_iss_is_eretax(esr)) { > + if (!(vcpu_has_ptrauth(vcpu) && kvm_auth_eretax(vcpu, &elr))) > + return false; > + } else { > + elr = read_sysreg_el1(SYS_ELR); > + } > + > spsr = (spsr & ~(PSR_MODE_MASK | PSR_MODE32_BIT)) | mode; > > write_sysreg_el2(spsr, SYS_SPSR); > - write_sysreg_el2(read_sysreg_el1(SYS_ELR), SYS_ELR); > + write_sysreg_el2(elr, SYS_ELR); > > return true; > } > Reviewed-by: Joey Gouly <joey.gouly@arm.com> Thanks, Joey
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c index 63a74c0330f1..72d733c74a38 100644 --- a/arch/arm64/kvm/emulate-nested.c +++ b/arch/arm64/kvm/emulate-nested.c @@ -2172,7 +2172,7 @@ static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr) void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) { - u64 spsr, elr; + u64 spsr, elr, esr; /* * Forward this trap to the virtual EL2 if the virtual @@ -2181,12 +2181,30 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) if (forward_traps(vcpu, HCR_NV)) return; + /* Check for an ERETAx */ + esr = kvm_vcpu_get_esr(vcpu); + if (esr_iss_is_eretax(esr) && !kvm_auth_eretax(vcpu, &elr)) { + /* + * Oh no, ERETAx failed to authenticate. If we have + * FPACCOMBINE, deliver an exception right away. If we + * don't, then let the mangled ELR value trickle down the + * ERET handling, and the guest will have a little surprise. + */ + if (kvm_has_pauth(vcpu->kvm, FPACCOMBINE)) { + esr &= ESR_ELx_ERET_ISS_ERETA; + esr |= FIELD_PREP(ESR_ELx_EC_MASK, ESR_ELx_EC_FPAC); + kvm_inject_nested_sync(vcpu, esr); + return; + } + } + preempt_disable(); kvm_arch_vcpu_put(vcpu); spsr = __vcpu_sys_reg(vcpu, SPSR_EL2); spsr = kvm_check_illegal_exception_return(vcpu, spsr); - elr = __vcpu_sys_reg(vcpu, ELR_EL2); + if (!esr_iss_is_eretax(esr)) + elr = __vcpu_sys_reg(vcpu, ELR_EL2); trace_kvm_nested_eret(vcpu, elr, spsr); diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 1ba2f788b2c3..407bdfbb572b 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -248,7 +248,8 @@ static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) static int kvm_handle_eret(struct kvm_vcpu *vcpu) { - if (esr_iss_is_eretax(kvm_vcpu_get_esr(vcpu))) + if (esr_iss_is_eretax(kvm_vcpu_get_esr(vcpu)) && + !vcpu_has_ptrauth(vcpu)) return kvm_handle_ptrauth(vcpu); /* diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 3ea9bdf6b555..49d36666040e 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -208,7 +208,8 @@ void kvm_vcpu_put_vhe(struct kvm_vcpu *vcpu) static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) { - u64 spsr, mode; + u64 esr = kvm_vcpu_get_esr(vcpu); + u64 spsr, elr, mode; /* * Going through the whole put/load motions is a waste of time @@ -242,10 +243,18 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code) return false; } + /* If ERETAx fails, take the slow path */ + if (esr_iss_is_eretax(esr)) { + if (!(vcpu_has_ptrauth(vcpu) && kvm_auth_eretax(vcpu, &elr))) + return false; + } else { + elr = read_sysreg_el1(SYS_ELR); + } + spsr = (spsr & ~(PSR_MODE_MASK | PSR_MODE32_BIT)) | mode; write_sysreg_el2(spsr, SYS_SPSR); - write_sysreg_el2(read_sysreg_el1(SYS_ELR), SYS_ELR); + write_sysreg_el2(elr, SYS_ELR); return true; }
Now that we have some emulation in place for ERETA[AB], we can plug it into the exception handling machinery. As for a bare ERET, an "easy" ERETAx instruction is processed as a fixup, while something that requires a translation regime transition or an exception delivery is left to the slow path. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/kvm/emulate-nested.c | 22 ++++++++++++++++++++-- arch/arm64/kvm/handle_exit.c | 3 ++- arch/arm64/kvm/hyp/vhe/switch.c | 13 +++++++++++-- 3 files changed, 33 insertions(+), 5 deletions(-)