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From: Marc Zyngier <maz@kernel.org>
To: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: kernel-team@android.com, Dave Martin <Dave.Martin@arm.com>
Subject: [PATCH v2 5/5] KVM: arm64: Simplify PtrAuth alternative patching
Date: Mon, 22 Jun 2020 09:06:43 +0100	[thread overview]
Message-ID: <20200622080643.171651-6-maz@kernel.org> (raw)
In-Reply-To: <20200622080643.171651-1-maz@kernel.org>

We currently decide to execute the PtrAuth save/restore code based
on a set of branches that evaluate as (ARM64_HAS_ADDRESS_AUTH_ARCH ||
ARM64_HAS_ADDRESS_AUTH_IMP_DEF). This can be easily replaced by
a much simpler test as the ARM64_HAS_ADDRESS_AUTH capability is
exactly this expression.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_ptrauth.h | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_ptrauth.h b/arch/arm64/include/asm/kvm_ptrauth.h
index f1830173fa9e..7a72508a841b 100644
--- a/arch/arm64/include/asm/kvm_ptrauth.h
+++ b/arch/arm64/include/asm/kvm_ptrauth.h
@@ -61,44 +61,36 @@
 
 /*
  * Both ptrauth_switch_to_guest and ptrauth_switch_to_host macros will
- * check for the presence of one of the cpufeature flag
- * ARM64_HAS_ADDRESS_AUTH_ARCH or ARM64_HAS_ADDRESS_AUTH_IMP_DEF and
+ * check for the presence ARM64_HAS_ADDRESS_AUTH, which is defined as
+ * (ARM64_HAS_ADDRESS_AUTH_ARCH || ARM64_HAS_ADDRESS_AUTH_IMP_DEF) and
  * then proceed ahead with the save/restore of Pointer Authentication
- * key registers.
+ * key registers if enabled for the guest.
  */
 .macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3
-alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
 	b	1000f
 alternative_else_nop_endif
-alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF
-	b	1001f
-alternative_else_nop_endif
-1000:
 	mrs	\reg1, hcr_el2
 	and	\reg1, \reg1, #(HCR_API | HCR_APK)
-	cbz	\reg1, 1001f
+	cbz	\reg1, 1000f
 	add	\reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_restore_state	\reg1, \reg2, \reg3
-1001:
+1000:
 .endm
 
 .macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3
-alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
 	b	2000f
 alternative_else_nop_endif
-alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF
-	b	2001f
-alternative_else_nop_endif
-2000:
 	mrs	\reg1, hcr_el2
 	and	\reg1, \reg1, #(HCR_API | HCR_APK)
-	cbz	\reg1, 2001f
+	cbz	\reg1, 2000f
 	add	\reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_save_state	\reg1, \reg2, \reg3
 	add	\reg1, \h_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_restore_state	\reg1, \reg2, \reg3
 	isb
-2001:
+2000:
 .endm
 
 #else /* !CONFIG_ARM64_PTR_AUTH */
-- 
2.27.0

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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Andrew Scull <ascull@google.com>,
	Dave Martin <Dave.Martin@arm.com>,
	kernel-team@android.com
Subject: [PATCH v2 5/5] KVM: arm64: Simplify PtrAuth alternative patching
Date: Mon, 22 Jun 2020 09:06:43 +0100	[thread overview]
Message-ID: <20200622080643.171651-6-maz@kernel.org> (raw)
In-Reply-To: <20200622080643.171651-1-maz@kernel.org>

We currently decide to execute the PtrAuth save/restore code based
on a set of branches that evaluate as (ARM64_HAS_ADDRESS_AUTH_ARCH ||
ARM64_HAS_ADDRESS_AUTH_IMP_DEF). This can be easily replaced by
a much simpler test as the ARM64_HAS_ADDRESS_AUTH capability is
exactly this expression.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_ptrauth.h | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_ptrauth.h b/arch/arm64/include/asm/kvm_ptrauth.h
index f1830173fa9e..7a72508a841b 100644
--- a/arch/arm64/include/asm/kvm_ptrauth.h
+++ b/arch/arm64/include/asm/kvm_ptrauth.h
@@ -61,44 +61,36 @@
 
 /*
  * Both ptrauth_switch_to_guest and ptrauth_switch_to_host macros will
- * check for the presence of one of the cpufeature flag
- * ARM64_HAS_ADDRESS_AUTH_ARCH or ARM64_HAS_ADDRESS_AUTH_IMP_DEF and
+ * check for the presence ARM64_HAS_ADDRESS_AUTH, which is defined as
+ * (ARM64_HAS_ADDRESS_AUTH_ARCH || ARM64_HAS_ADDRESS_AUTH_IMP_DEF) and
  * then proceed ahead with the save/restore of Pointer Authentication
- * key registers.
+ * key registers if enabled for the guest.
  */
 .macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3
-alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
 	b	1000f
 alternative_else_nop_endif
-alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF
-	b	1001f
-alternative_else_nop_endif
-1000:
 	mrs	\reg1, hcr_el2
 	and	\reg1, \reg1, #(HCR_API | HCR_APK)
-	cbz	\reg1, 1001f
+	cbz	\reg1, 1000f
 	add	\reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_restore_state	\reg1, \reg2, \reg3
-1001:
+1000:
 .endm
 
 .macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3
-alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH
+alternative_if_not ARM64_HAS_ADDRESS_AUTH
 	b	2000f
 alternative_else_nop_endif
-alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF
-	b	2001f
-alternative_else_nop_endif
-2000:
 	mrs	\reg1, hcr_el2
 	and	\reg1, \reg1, #(HCR_API | HCR_APK)
-	cbz	\reg1, 2001f
+	cbz	\reg1, 2000f
 	add	\reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_save_state	\reg1, \reg2, \reg3
 	add	\reg1, \h_ctxt, #CPU_APIAKEYLO_EL1
 	ptrauth_restore_state	\reg1, \reg2, \reg3
 	isb
-2001:
+2000:
 .endm
 
 #else /* !CONFIG_ARM64_PTR_AUTH */
-- 
2.27.0


  parent reply	other threads:[~2020-06-22  8:07 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-22  8:06 [PATCH v2 0/5] KVM/arm64: Enable PtrAuth on non-VHE KVM Marc Zyngier
2020-06-22  8:06 ` Marc Zyngier
2020-06-22  8:06 ` [PATCH v2 1/5] KVM: arm64: Enable Address Authentication at EL2 if available Marc Zyngier
2020-06-22  8:06   ` Marc Zyngier
2020-06-22  9:04   ` Mark Rutland
2020-06-22  9:04     ` Mark Rutland
2020-06-22  8:06 ` [PATCH v2 2/5] KVM: arm64: Allow ARM64_PTR_AUTH when ARM64_VHE=n Marc Zyngier
2020-06-22  8:06   ` Marc Zyngier
2020-06-22  8:06 ` [PATCH v2 3/5] KVM: arm64: Allow PtrAuth to be enabled from userspace on non-VHE systems Marc Zyngier
2020-06-22  8:06   ` Marc Zyngier
2020-06-22  8:06 ` [PATCH v2 4/5] KVM: arm64: Check HCR_EL2 instead of shadow copy to swap PtrAuth registers Marc Zyngier
2020-06-22  8:06   ` Marc Zyngier
2020-06-22  8:06 ` Marc Zyngier [this message]
2020-06-22  8:06   ` [PATCH v2 5/5] KVM: arm64: Simplify PtrAuth alternative patching Marc Zyngier
2020-06-22  9:15   ` Mark Rutland
2020-06-22  9:15     ` Mark Rutland
2020-06-22 10:25     ` Marc Zyngier
2020-06-22 10:25       ` Marc Zyngier
2020-06-22 10:31       ` Mark Rutland
2020-06-22 10:31         ` Mark Rutland
2020-06-22 10:39     ` Andrew Scull
2020-06-22 10:39       ` Andrew Scull
2020-06-22 10:43       ` Andrew Scull
2020-06-22 10:43         ` Andrew Scull

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