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From: Russell King <rmk+kernel@armlinux.org.uk>
To: linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	kvmarm@lists.cs.columbia.edu
Subject: [PATCH v3 14/15] ARM: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling
Date: Fri, 25 May 2018 15:01:34 +0100	[thread overview]
Message-ID: <E1fMDHi-000746-Fu@rmk-PC.armlinux.org.uk> (raw)
In-Reply-To: <20180525135938.GE17671@n2100.armlinux.org.uk>

We want SMCCC_ARCH_WORKAROUND_1 to be fast. As fast as possible.
So let's intercept it as early as we can by testing for the
function call number as soon as we've identified a HVC call
coming from the guest.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 arch/arm/kvm/hyp/hyp-entry.S | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S
index 918a05dd2d63..aa3f9a9837ac 100644
--- a/arch/arm/kvm/hyp/hyp-entry.S
+++ b/arch/arm/kvm/hyp/hyp-entry.S
@@ -16,6 +16,7 @@
  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <linux/arm-smccc.h>
 #include <linux/linkage.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
@@ -202,7 +203,7 @@ ENDPROC(__hyp_do_panic)
 	lsr     r2, r2, #16
 	and     r2, r2, #0xff
 	cmp     r2, #0
-	bne	guest_trap		@ Guest called HVC
+	bne	guest_hvc_trap		@ Guest called HVC
 
 	/*
 	 * Getting here means host called HVC, we shift parameters and branch
@@ -253,6 +254,20 @@ THUMB(	orr	lr, #1)
 	pop	{r2, lr}
 	eret
 
+guest_hvc_trap:
+	movw	r2, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
+	movt	r2, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
+	ldr	r0, [sp]		@ Guest's r0
+	teq	r0, r2
+	bne	guest_trap
+	add	sp, sp, #12
+	@ Returns:
+	@ r0 = 0
+	@ r1 = HSR value (perfectly predictable)
+	@ r2 = ARM_SMCCC_ARCH_WORKAROUND_1
+	mov	r0, #0
+	eret
+
 guest_trap:
 	load_vcpu r0			@ Load VCPU pointer to r0
 
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)
From: rmk+kernel@armlinux.org.uk (Russell King)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 14/15] ARM: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling
Date: Fri, 25 May 2018 15:01:34 +0100	[thread overview]
Message-ID: <E1fMDHi-000746-Fu@rmk-PC.armlinux.org.uk> (raw)
In-Reply-To: <20180525135938.GE17671@n2100.armlinux.org.uk>

We want SMCCC_ARCH_WORKAROUND_1 to be fast. As fast as possible.
So let's intercept it as early as we can by testing for the
function call number as soon as we've identified a HVC call
coming from the guest.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 arch/arm/kvm/hyp/hyp-entry.S | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S
index 918a05dd2d63..aa3f9a9837ac 100644
--- a/arch/arm/kvm/hyp/hyp-entry.S
+++ b/arch/arm/kvm/hyp/hyp-entry.S
@@ -16,6 +16,7 @@
  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <linux/arm-smccc.h>
 #include <linux/linkage.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
@@ -202,7 +203,7 @@ ENDPROC(__hyp_do_panic)
 	lsr     r2, r2, #16
 	and     r2, r2, #0xff
 	cmp     r2, #0
-	bne	guest_trap		@ Guest called HVC
+	bne	guest_hvc_trap		@ Guest called HVC
 
 	/*
 	 * Getting here means host called HVC, we shift parameters and branch
@@ -253,6 +254,20 @@ THUMB(	orr	lr, #1)
 	pop	{r2, lr}
 	eret
 
+guest_hvc_trap:
+	movw	r2, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
+	movt	r2, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
+	ldr	r0, [sp]		@ Guest's r0
+	teq	r0, r2
+	bne	guest_trap
+	add	sp, sp, #12
+	@ Returns:
+	@ r0 = 0
+	@ r1 = HSR value (perfectly predictable)
+	@ r2 = ARM_SMCCC_ARCH_WORKAROUND_1
+	mov	r0, #0
+	eret
+
 guest_trap:
 	load_vcpu r0			@ Load VCPU pointer to r0
 
-- 
2.7.4

  parent reply	other threads:[~2018-05-25 13:52 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-25 13:59 [PATCH v3 00/15] ARM Spectre variant 2 fixes Russell King - ARM Linux
2018-05-25 13:59 ` Russell King - ARM Linux
2018-05-25 14:00 ` [PATCH v3 01/15] ARM: add more CPU part numbers for Cortex and Brahma B15 CPUs Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 02/15] ARM: bugs: prepare processor bug infrastructure Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 03/15] ARM: bugs: hook processor bug checking into SMP and suspend paths Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 04/15] ARM: bugs: add support for per-processor bug checking Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 05/15] ARM: spectre: add Kconfig symbol for CPUs vulnerable to Spectre Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 06/15] ARM: spectre-v2: harden branch predictor on context switches Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:00 ` [PATCH v3 07/15] ARM: spectre-v2: add Cortex A8 and A15 validation of the IBE bit Russell King
2018-05-25 14:00   ` Russell King
2018-05-25 14:01 ` [PATCH v3 08/15] ARM: spectre-v2: harden user aborts in kernel space Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 15:47   ` Tony Lindgren
2018-05-25 15:47     ` Tony Lindgren
2018-05-25 15:52     ` Russell King - ARM Linux
2018-05-25 15:52       ` Russell King - ARM Linux
2018-05-25 16:01       ` Tony Lindgren
2018-05-25 16:01         ` Tony Lindgren
2018-05-25 16:15         ` Tony Lindgren
2018-05-25 16:15           ` Tony Lindgren
2018-05-25 14:01 ` [PATCH v3 09/15] ARM: spectre-v2: add firmware based hardening Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 14:01 ` [PATCH v3 10/15] ARM: spectre-v2: warn about incorrect context switching functions Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 14:01 ` [PATCH v3 11/15] ARM: KVM: invalidate BTB on guest exit for Cortex-A12/A17 Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 14:01 ` [PATCH v3 12/15] ARM: KVM: invalidate icache on guest exit for Cortex-A15 Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 14:01 ` [PATCH v3 13/15] ARM: spectre-v2: KVM: invalidate icache on guest exit for Brahma B15 Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 14:01 ` Russell King [this message]
2018-05-25 14:01   ` [PATCH v3 14/15] ARM: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling Russell King
2018-05-25 14:01 ` [PATCH v3 15/15] ARM: KVM: report support for SMCCC_ARCH_WORKAROUND_1 Russell King
2018-05-25 14:01   ` Russell King
2018-05-25 16:25 ` [PATCH v3 00/15] ARM Spectre variant 2 fixes Tony Lindgren
2018-05-25 16:25   ` Tony Lindgren

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