From: Will Deacon <will.deacon@arm.com> mainline inclusion from v5.0-rc1 commit 679db70801da9fda91d26caf13bf5b5ccc74e8e8 category: feature bugzilla: 30102 CVE: NA ------------------------------------------------- Some CPUs can speculate past an ERET instruction and potentially perform speculative accesses to memory before processing the exception return. Since the register state is often controlled by a lower privilege level at the point of an ERET, this could potentially be used as part of a side-channel attack. This patch emits an SB sequence after each ERET so that speculation is held up on exception return. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com> Reviewed-by: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- arch/arm64/kernel/entry.S | 2 ++ arch/arm64/kvm/hyp/entry.S | 1 + arch/arm64/kvm/hyp/hyp-entry.S | 4 ++++ 3 files changed, 7 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f5c863b09c13..286f8d3bd10f 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -380,6 +380,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 .else eret .endif + sb .endm .macro irq_stack_entry @@ -1094,6 +1095,7 @@ alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 mrs x30, far_el1 .endif eret + sb .endm .align 11 diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index fad1e164fe48..675fdc186e3b 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -83,6 +83,7 @@ ENTRY(__guest_enter) // Do not touch any register after this! eret + sb ENDPROC(__guest_enter) ENTRY(__guest_exit) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index b1f14f736962..73c1b483ec39 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -96,6 +96,7 @@ el1_sync: // Guest trapped into EL2 do_el2_call eret + sb el1_hvc_guest: /* @@ -146,6 +147,7 @@ wa_epilogue: mov x0, xzr add sp, sp, #16 eret + sb el1_trap: get_vcpu_ptr x1, x0 @@ -199,6 +201,7 @@ el2_error: b.ne __hyp_panic mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT) eret + sb ENTRY(__hyp_do_panic) mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\ @@ -207,6 +210,7 @@ ENTRY(__hyp_do_panic) ldr lr, =panic msr elr_el2, lr eret + sb ENDPROC(__hyp_do_panic) ENTRY(__hyp_panic) -- 2.25.1