arm64: Don't trap host pointer auth use to EL2

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.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index c8825c5a8dd012d423b5aabbed567a9319c0c227..f9123fe8fcf367307b510e1f3c9aca152d293a18 100644 (file)
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -24,6 +24,8 @@
 
 /* Hyp Configuration Register (HCR) bits */
 #define HCR_FWB                (UL(1) << 46)
+#define HCR_API                (UL(1) << 41)
+#define HCR_APK                (UL(1) << 40)
 #define HCR_TEA                (UL(1) << 37)
 #define HCR_TERR       (UL(1) << 36)
 #define HCR_TLOR       (UL(1) << 35)
@@ -87,7 +89,7 @@
                         HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
                         HCR_FMO | HCR_IMO)
 #define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
-#define HCR_HOST_NVHE_FLAGS (HCR_RW)
+#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK)
 #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
 
 /* TCR_EL2 Registers bits */