Hi Marc,
On Mon, Nov 29, 2021 at 08:00:57PM +0000, Marc Zyngier wrote:
> From: Christoffer Dall <christoffer.dall@xxxxxxx>
>
> When a guest hypervisor running virtual EL2 in EL1 executes an ERET
> instruction, we will have set HCR_EL2.NV which traps ERET to EL2, so
> that we can emulate the exception return in software.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/esr.h | 5 +++++
> arch/arm64/include/asm/kvm_arm.h | 2 +-
> arch/arm64/kvm/handle_exit.c | 10 ++++++++++
> 3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
> index d52a0b269ee8..6835e4231119 100644
> --- a/arch/arm64/include/asm/esr.h
> +++ b/arch/arm64/include/asm/esr.h
> @@ -257,6 +257,11 @@
> (((e) & ESR_ELx_SYS64_ISS_OP2_MASK) >> \
> ESR_ELx_SYS64_ISS_OP2_SHIFT))
>
> +/* ISS field definitions for ERET/ERETAA/ERETAB trapping */
> +
> +#define ESR_ELx_ERET_ISS_ERET_ERETAx 0x2
> +#define ESR_ELx_ERET_ISS_ERETA_ERATAB 0x1
^^^^^
Shouldn't that be ERETAA?
Other than that, the patch looks good to me, although I'm unfamiliar with
PAuth:
Reviewed-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Thanks,
Alex
> +
> /*
> * ISS field definitions for floating-point exception traps
> * (FP_EXC_32/FP_EXC_64).
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index 589a6b92d741..0a0ee998ec5a 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -353,7 +353,7 @@
> ECN(SP_ALIGN), ECN(FP_EXC32), ECN(FP_EXC64), ECN(SERROR), \
> ECN(BREAKPT_LOW), ECN(BREAKPT_CUR), ECN(SOFTSTP_LOW), \
> ECN(SOFTSTP_CUR), ECN(WATCHPT_LOW), ECN(WATCHPT_CUR), \
> - ECN(BKPT32), ECN(VECTOR32), ECN(BRK64)
> + ECN(BKPT32), ECN(VECTOR32), ECN(BRK64), ECN(ERET)
>
> #define CPACR_EL1_FPEN (3 << 20)
> #define CPACR_EL1_TTA (1 << 28)
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 1fd1c6dfd6a0..95ae624d6aa8 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -169,6 +169,15 @@ static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
> return 1;
> }
>
> +static int kvm_handle_eret(struct kvm_vcpu *vcpu)
> +{
> + if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_ERET_ISS_ERET_ERETAx)
> + return kvm_handle_ptrauth(vcpu);
> +
> + kvm_emulate_nested_eret(vcpu);
> + return 1;
> +}
> +
> static exit_handle_fn arm_exit_handlers[] = {
> [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
> [ESR_ELx_EC_WFx] = kvm_handle_wfx,
> @@ -183,6 +192,7 @@ static exit_handle_fn arm_exit_handlers[] = {
> [ESR_ELx_EC_SMC64] = handle_smc,
> [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
> [ESR_ELx_EC_SVE] = handle_sve,
> + [ESR_ELx_EC_ERET] = kvm_handle_eret,
> [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
> [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
> [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
> --
> 2.30.2
>
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