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KVM: arm64: nv: Handle ERETA[AB] instructions

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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.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240419102935.1935571-14-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2024-04-19 11:29:33 +01:00
parent 6ccc971ee2
commit 213b3d1ea1
3 changed files with 33 additions and 5 deletions
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20
arch/arm64/kvm/emulate-nested.c
View file

@ -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) 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 * Forward this trap to the virtual EL2 if the virtual
@ -2181,11 +2181,29 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu)
if (forward_traps(vcpu, HCR_NV)) if (forward_traps(vcpu, HCR_NV))
return; 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(); preempt_disable();
kvm_arch_vcpu_put(vcpu); kvm_arch_vcpu_put(vcpu);
spsr = __vcpu_sys_reg(vcpu, SPSR_EL2); spsr = __vcpu_sys_reg(vcpu, SPSR_EL2);
spsr = kvm_check_illegal_exception_return(vcpu, spsr); spsr = kvm_check_illegal_exception_return(vcpu, spsr);
if (!esr_iss_is_eretax(esr))
elr = __vcpu_sys_reg(vcpu, ELR_EL2); elr = __vcpu_sys_reg(vcpu, ELR_EL2);
trace_kvm_nested_eret(vcpu, elr, spsr); trace_kvm_nested_eret(vcpu, elr, spsr);

3
arch/arm64/kvm/handle_exit.c
View file

@ -248,7 +248,8 @@ static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
static int kvm_handle_eret(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); return kvm_handle_ptrauth(vcpu);
/* /*

13
arch/arm64/kvm/hyp/vhe/switch.c
View file

@ -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) 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 * 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; 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; spsr = (spsr & ~(PSR_MODE_MASK | PSR_MODE32_BIT)) | mode;
write_sysreg_el2(spsr, SYS_SPSR); write_sysreg_el2(spsr, SYS_SPSR);
write_sysreg_el2(read_sysreg_el1(SYS_ELR), SYS_ELR); write_sysreg_el2(elr, SYS_ELR);
return true; return true;
} }