diff mbox series

[4.9,12/24] ARM: KVM: invalidate icache on guest exit for Cortex-A15

Message ID 20181031135713.2873-13-dave.long@linaro.org
State Superseded
Headers show
Series V4.9 backport of 32-bit arm spectre patches | expand

Commit Message

David Long Oct. 31, 2018, 1:57 p.m. UTC 
From: Marc Zyngier <marc.zyngier@arm.com>


Commit 0c47ac8cd157727e7a532d665d6fb1b5fd333977 upstream.

In order to avoid aliasing attacks against the branch predictor
on Cortex-A15, let's invalidate the BTB on guest exit, which can
only be done by invalidating the icache (with ACTLR[0] being set).

We use the same hack as for A12/A17 to perform the vector decoding.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>

Signed-off-by: David A. Long <dave.long@linaro.org>

---
 arch/arm/include/asm/kvm_mmu.h |  5 +++++
 arch/arm/kvm/hyp/hyp-entry.S   | 24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

-- 
2.17.1
diff mbox series

Patch

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 625edef2a54f..3ad2c44f4137 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -257,6 +257,11 @@  static inline void *kvm_get_hyp_vector(void)
 		return kvm_ksym_ref(__kvm_hyp_vector_bp_inv);
 	}
 
+	case ARM_CPU_PART_CORTEX_A15:
+	{
+		extern char __kvm_hyp_vector_ic_inv[];
+		return kvm_ksym_ref(__kvm_hyp_vector_ic_inv);
+	}
 #endif
 	default:
 	{
diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S
index de242d9598c6..582f50759d80 100644
--- a/arch/arm/kvm/hyp/hyp-entry.S
+++ b/arch/arm/kvm/hyp/hyp-entry.S
@@ -72,6 +72,28 @@  __kvm_hyp_vector:
 	W(b)	hyp_fiq
 
 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+	.align 5
+__kvm_hyp_vector_ic_inv:
+	.global __kvm_hyp_vector_ic_inv
+
+	/*
+	 * We encode the exception entry in the bottom 3 bits of
+	 * SP, and we have to guarantee to be 8 bytes aligned.
+	 */
+	W(add)	sp, sp, #1	/* Reset 	  7 */
+	W(add)	sp, sp, #1	/* Undef	  6 */
+	W(add)	sp, sp, #1	/* Syscall	  5 */
+	W(add)	sp, sp, #1	/* Prefetch abort 4 */
+	W(add)	sp, sp, #1	/* Data abort	  3 */
+	W(add)	sp, sp, #1	/* HVC		  2 */
+	W(add)	sp, sp, #1	/* IRQ		  1 */
+	W(nop)			/* FIQ		  0 */
+
+	mcr	p15, 0, r0, c7, c5, 0	/* ICIALLU */
+	isb
+
+	b	decode_vectors
+
 	.align 5
 __kvm_hyp_vector_bp_inv:
 	.global __kvm_hyp_vector_bp_inv
@@ -92,6 +114,8 @@  __kvm_hyp_vector_bp_inv:
 	mcr	p15, 0, r0, c7, c5, 6	/* BPIALL */
 	isb
 
+decode_vectors:
+
 #ifdef CONFIG_THUMB2_KERNEL
 	/*
 	 * Yet another silly hack: Use VPIDR as a temp register.