AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2025-01-18 17:16:27 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

ARM: KVM: invalidate BTB on guest exit for Cortex-A12/A17

Browse Source 
In order to avoid aliasing attacks against the branch predictor,
let's invalidate the BTB on guest exit. This is made complicated
by the fact that we cannot take a branch before invalidating the
BTB.

We only apply this to A12 and A17, which are the only two ARM
cores on which this useful.

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 11:07:35 +00:00 committed by Russell King
parent c44f366ea7
commit 3f7e8e2e1e
3 changed files with 85 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm/include/asm/kvm_asm.h
View File

@ -61,8 +61,6 @@ struct kvm_vcpu;
extern char __kvm_hyp_init[];
extern char __kvm_hyp_init_end[];
extern char __kvm_hyp_vector[];
extern void __kvm_flush_vm_context(void);
extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
extern void __kvm_tlb_flush_vmid(struct kvm *kvm);

17
arch/arm/include/asm/kvm_mmu.h
View File

@ -297,7 +297,22 @@ static inline unsigned int kvm_get_vmid_bits(void)
static inline void *kvm_get_hyp_vector(void)
{
return kvm_ksym_ref(__kvm_hyp_vector);
switch(read_cpuid_part()) {
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
case ARM_CPU_PART_CORTEX_A12:
case ARM_CPU_PART_CORTEX_A17:
{
extern char __kvm_hyp_vector_bp_inv[];
return kvm_ksym_ref(__kvm_hyp_vector_bp_inv);
}
#endif
default:
{
extern char __kvm_hyp_vector[];
return kvm_ksym_ref(__kvm_hyp_vector);
}
}
}
static inline int kvm_map_vectors(void)

71
arch/arm/kvm/hyp/hyp-entry.S
View File

@ -71,6 +71,66 @@ __kvm_hyp_vector:
W(b) hyp_irq
W(b) hyp_fiq
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
.align 5
__kvm_hyp_vector_bp_inv:
.global __kvm_hyp_vector_bp_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, 6 /* BPIALL */
isb
#ifdef CONFIG_THUMB2_KERNEL
/*
* Yet another silly hack: Use VPIDR as a temp register.
* Thumb2 is really a pain, as SP cannot be used with most
* of the bitwise instructions. The vect_br macro ensures
* things gets cleaned-up.
*/
mcr p15, 4, r0, c0, c0, 0 /* VPIDR */
mov r0, sp
and r0, r0, #7
sub sp, sp, r0
push {r1, r2}
mov r1, r0
mrc p15, 4, r0, c0, c0, 0 /* VPIDR */
mrc p15, 0, r2, c0, c0, 0 /* MIDR */
mcr p15, 4, r2, c0, c0, 0 /* VPIDR */
#endif
.macro vect_br val, targ
ARM( eor sp, sp, #\val )
ARM( tst sp, #7 )
ARM( eorne sp, sp, #\val )
THUMB( cmp r1, #\val )
THUMB( popeq {r1, r2} )
beq \targ
.endm
vect_br 0, hyp_fiq
vect_br 1, hyp_irq
vect_br 2, hyp_hvc
vect_br 3, hyp_dabt
vect_br 4, hyp_pabt
vect_br 5, hyp_svc
vect_br 6, hyp_undef
vect_br 7, hyp_reset
#endif
.macro invalid_vector label, cause
.align
\label: mov r0, #\cause
@ -149,7 +209,14 @@ hyp_hvc:
bx ip
1:
push {lr}
/*
* Pushing r2 here is just a way of keeping the stack aligned to
* 8 bytes on any path that can trigger a HYP exception. Here,
* we may well be about to jump into the guest, and the guest
* exit would otherwise be badly decoded by our fancy
* "decode-exception-without-a-branch" code...
*/
push {r2, lr}
mov lr, r0
mov r0, r1
@ -159,7 +226,7 @@ hyp_hvc:
THUMB( orr lr, #1)
blx lr @ Call the HYP function
pop {lr}
pop {r2, lr}
eret
guest_trap: