Re: [PATCH 1/4] KVM: arm64: Enable Pointer Authentication at EL2 if available

Hi Andrew,

On 2020-06-15 09:48, Andrew Scull wrote:

On Mon, Jun 15, 2020 at 09:19:51AM +0100, Marc Zyngier wrote:

quoted

While initializing EL2, switch Pointer Authentication if detected

                                ^ nit: on?

Yes.

quoted

from EL1. We use the EL1-provided keys though.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hyp-init.S | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index 6e6ed5581eed..81732177507d 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S

@@ -104,6 +104,17 @@ alternative_else_nop_endif
 	 */
 	mov_q	x4, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
 CPU_BE(	orr	x4, x4, #SCTLR_ELx_EE)
+alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH
+	b	1f
+alternative_else_nop_endif
+alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF
+	b	2f
+alternative_else_nop_endif
+1:
+	orr	x4, x4, #(SCTLR_ELx_ENIA | SCTLR_ELx_ENIB)
+	orr	x4, x4, #SCTLR_ELx_ENDA
+	orr	x4, x4, #SCTLR_ELx_ENDB

mm/proc.S builds the mask with ldr and ors it in one go, would be nice
to use the same pattern.

Do you actually mean kernel/head.S, or even __ptrauth_keys_init_cpu in 
asm/asm_pointer_auth.h?

If so, I agree that it'd be good to make it look similar by using the 
mov_q macro, at the expense of a spare register (which we definitely can 
afford here).

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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