Hi Marc,
On 26/10/2020 13:34, Marc Zyngier wrote:
> Similarily to what has been done for AArch64, move the AArch32 exception
> inhjection to HYP.
>
> In order to not use the regmap selection code at EL2, simplify the code
> populating the target mode's LR register by harcoding the two possible
> LR registers (LR_abt in X20, LR_und in X22).
> diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
> index cd6e643639e8..8d1d1bcd9e69 100644
> --- a/arch/arm64/kvm/hyp/exception.c
> +++ b/arch/arm64/kvm/hyp/exception.c
> @@ -57,10 +67,25 @@ static void __vcpu_write_spsr(struct kvm_vcpu *vcpu, u64 val)
> +static inline u32 __vcpu_read_cp15(const struct kvm_vcpu *vcpu, int reg)
> +{
> + return __vcpu_read_sys_reg(vcpu, reg / 2);
> +}
Doesn't this re-implement the issue 3204be4109ad biased?
> @@ -155,23 +180,189 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
> +static void enter_exception32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset)
> +{
> + /*
> + * Table D1-27 of DDI 0487F.c shows the GPR mapping between
> + * AArch32 and AArch64. We only deal with ABT/UND.
(to check I understand : because these are the only two KVM ever injects?)
> + */
> + switch(mode) {
> + case PSR_AA32_MODE_ABT:
> + __vcpu_write_spsr_abt(vcpu, host_spsr_to_spsr32(spsr));
> + lr = 20;
> break;
> +
(two bonus tabs!)
> + case PSR_AA32_MODE_UND:
> + __vcpu_write_spsr_und(vcpu, host_spsr_to_spsr32(spsr));
> + lr = 22;
> break;
> }> +
> + vcpu_set_reg(vcpu, lr, *vcpu_pc(vcpu) + return_offset);
Can we, abuse, the compat_lr_abt definitions to do something like:
| u32 return_address = *vcpu_pc(vcpu) + return_offset;
[..]
| switch(mode) {
| case PSR_AA32_MODE_ABT:>
| __vcpu_write_spsr_abt(vcpu, host_spsr_to_spsr32(spsr));
| vcpu_gp_regs(vcpu)->compat_lr_abt = return_address;
| break;
| case PSR_AA32_MODE_UND:
| __vcpu_write_spsr_und(vcpu, host_spsr_to_spsr32(spsr));
| vcpu_gp_regs(vcpu)->compat_lr_und = return_address;
| break;
...as someone who has no clue about 32bit, this hides all the worrying magic-14==magic-22!
Thanks,
James
> +}
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