Re: [PATCH v6 05/13] arm64: Don't trap host pointer auth use to EL2

From: Richard Henderson
Date: Sun Dec 09 2018 - 09:55:15 EST

On 12/7/18 12:39 PM, Kristina Martsenko wrote:
> From: Mark Rutland <mark.rutland@xxxxxxx>
> To allow EL0 (and/or EL1) to use pointer authentication functionality,
> we must ensure that pointer authentication instructions and accesses to
> pointer authentication keys are not trapped to EL2.
> This patch ensures that HCR_EL2 is configured appropriately when the
> kernel is booted at EL2. For non-VHE kernels we set HCR_EL2.{API,APK},
> ensuring that EL1 can access keys and permit EL0 use of instructions.
> For VHE kernels host EL0 (TGE && E2H) is unaffected by these settings,
> and it doesn't matter how we configure HCR_EL2.{API,APK}, so we don't
> bother setting them.
> This does not enable support for KVM guests, since KVM manages HCR_EL2
> itself when running VMs.
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
> Acked-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
> ---
> arch/arm64/include/asm/kvm_arm.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@xxxxxxxxxx>