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Date: Tue, 17 Apr 2018 19:37:28 +0100
From: Mark Rutland <mark.rutland@....com>
To: linux-arm-kernel@...ts.infradead.org
Cc: arnd@...db.de,
catalin.marinas@....com,
cdall@...nel.org,
drjones@...hat.com,
kvmarm@...ts.cs.columbia.edu,
linux-arch@...r.kernel.org,
marc.zyngier@....com,
mark.rutland@....com,
ramana.radhakrishnan@....com,
suzuki.poulose@....com,
will.deacon@....com,
linux-kernel@...r.kernel.org,
awallis@...eaurora.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCHv3 04/11] 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.
Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Christoffer Dall <cdall@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: kvmarm@...ts.cs.columbia.edu
---
arch/arm64/include/asm/kvm_arm.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 89b3dda7e3cb..4d57e1e58323 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -23,6 +23,8 @@
#include <asm/types.h>
/* Hyp Configuration Register (HCR) bits */
+#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)
@@ -86,7 +88,7 @@
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 */
--
2.11.0
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