On 27/10/2022 13:09, Ryan Roberts wrote:
> enter_exception64() performs an MTE check, which involves dereferencing
> vcpu->kvm. While vcpu has already been fixed up for hyp va, kvm is still
> a kern va pointer.
>
> Fix this by first converting kvm to a hyp va pointer. If the system does
> not support MTE, the dereference is avoided in the first place.
>
> Fixes: ea7fc1bb1cd1 ("KVM: arm64: Introduce MTE VM feature")
>
> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
It's worth pointing out this only affects non-VHE mode, which is unusual
on hardware which supports MTE (and therefore VHE). But, of course,
about to get more usual with pKVM.
Reviewed-by: Steven Price <steven.price@xxxxxxx>
> ---
> arch/arm64/kvm/hyp/exception.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
> index b7557b25ed56..791d3de76771 100644
> --- a/arch/arm64/kvm/hyp/exception.c
> +++ b/arch/arm64/kvm/hyp/exception.c
> @@ -13,6 +13,7 @@
> #include <hyp/adjust_pc.h>
> #include <linux/kvm_host.h>
> #include <asm/kvm_emulate.h>
> +#include <asm/kvm_mmu.h>
>
> #if !defined (__KVM_NVHE_HYPERVISOR__) && !defined (__KVM_VHE_HYPERVISOR__)
> #error Hypervisor code only!
> @@ -115,7 +116,7 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
> new |= (old & PSR_C_BIT);
> new |= (old & PSR_V_BIT);
>
> - if (kvm_has_mte(vcpu->kvm))
> + if (kvm_has_mte(kern_hyp_va(vcpu->kvm)))
> new |= PSR_TCO_BIT;
>
> new |= (old & PSR_DIT_BIT);
> --
> 2.17.1
>
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