On Thu, Sep 23, 2021 at 07:16:01PM +0000, Oliver Upton wrote:
> The only valid calling SMC calling convention from an AArch32 state is
> SMC32. Disallow any PSCI function that sets the SMC64 function ID bit
> when called from AArch32 rather than comparing against known SMC64 PSCI
> functions.
>
> Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
> ---
> arch/arm64/kvm/psci.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> index d46842f45b0a..310b9cb2b32b 100644
> --- a/arch/arm64/kvm/psci.c
> +++ b/arch/arm64/kvm/psci.c
> @@ -208,15 +208,11 @@ static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
>
> static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn)
> {
> - switch(fn) {
> - case PSCI_0_2_FN64_CPU_SUSPEND:
> - case PSCI_0_2_FN64_CPU_ON:
> - case PSCI_0_2_FN64_AFFINITY_INFO:
> - /* Disallow these functions for 32bit guests */
> - if (vcpu_mode_is_32bit(vcpu))
> - return PSCI_RET_NOT_SUPPORTED;
> - break;
> - }
> + /*
> + * Prevent 32 bit guests from calling 64 bit PSCI functions.
> + */
> + if ((fn & PSCI_0_2_64BIT) && vcpu_mode_is_32bit(vcpu))
> + return PSCI_RET_NOT_SUPPORTED;
>
> return 0;
> }
> --
> 2.33.0.685.g46640cef36-goog
>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
