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ARM: KVM: invalidate icache on guest exit for Cortex-A15 

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>
This commit is contained in:
Marc Zyngier 2018-02-01 11:07:38 +00:00 committed by Russell King
parent 3f7e8e2e1e
commit 0c47ac8cd1
2 changed files with 29 additions and 0 deletions
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5
arch/arm/include/asm/kvm_mmu.h
View File

@ -306,6 +306,11 @@ 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:
{

24
arch/arm/kvm/hyp/hyp-entry.S
View File

@ -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.