This is a note to let you know that I've just added the patch titled
[Variant 2/Spectre-v2] arm64: KVM: Report SMCCC_ARCH_WORKAROUND_1 BP hardening support
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Feb 13 17:25:10 CET 2018
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Date: Tue, 6 Feb 2018 17:56:14 +0000
Subject: [Variant 2/Spectre-v2] arm64: KVM: Report SMCCC_ARCH_WORKAROUND_1 BP hardening support
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Commit 6167ec5c9145 upstream.
A new feature of SMCCC 1.1 is that it offers firmware-based CPU
workarounds. In particular, SMCCC_ARCH_WORKAROUND_1 provides
BP hardening for CVE-2017-5715.
If the host has some mitigation for this issue, report that
we deal with it using SMCCC_ARCH_WORKAROUND_1, as we apply the
host workaround on every guest exit.
Tested-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Conflicts:
arch/arm/include/asm/kvm_host.h
arch/arm64/include/asm/kvm_host.h
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 6 ++++++
arch/arm64/include/asm/kvm_host.h | 5 +++++
include/linux/arm-smccc.h | 5 +++++
virt/kvm/arm/psci.c | 9 ++++++++-
4 files changed, 24 insertions(+), 1 deletion(-)
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -301,4 +301,10 @@ int kvm_arm_vcpu_arch_has_attr(struct kv
/* All host FP/SIMD state is restored on guest exit, so nothing to save: */
static inline void kvm_fpsimd_flush_cpu_state(void) {}
+static inline bool kvm_arm_harden_branch_predictor(void)
+{
+ /* No way to detect it yet, pretend it is not there. */
+ return false;
+}
+
#endif /* __ARM_KVM_HOST_H__ */
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -396,4 +396,9 @@ static inline void kvm_fpsimd_flush_cpu_
sve_flush_cpu_state();
}
+static inline bool kvm_arm_harden_branch_predictor(void)
+{
+ return cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR);
+}
+
#endif /* __ARM64_KVM_HOST_H__ */
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -73,6 +73,11 @@
ARM_SMCCC_SMC_32, \
0, 1)
+#define ARM_SMCCC_ARCH_WORKAROUND_1 \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_32, \
+ 0, 0x8000)
+
#ifndef __ASSEMBLY__
#include <linux/linkage.h>
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -405,13 +405,20 @@ int kvm_hvc_call_handler(struct kvm_vcpu
{
u32 func_id = smccc_get_function(vcpu);
u32 val = PSCI_RET_NOT_SUPPORTED;
+ u32 feature;
switch (func_id) {
case ARM_SMCCC_VERSION_FUNC_ID:
val = ARM_SMCCC_VERSION_1_1;
break;
case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
- /* Nothing supported yet */
+ feature = smccc_get_arg1(vcpu);
+ switch(feature) {
+ case ARM_SMCCC_ARCH_WORKAROUND_1:
+ if (kvm_arm_harden_branch_predictor())
+ val = 0;
+ break;
+ }
break;
default:
return kvm_psci_call(vcpu);
Patches currently in stable-queue which might be from marc.zyngier@xxxxxxx are
queue-4.15/arm-arm64-smccc-make-function-identifiers-an-unsigned-quantity.patch
queue-4.15/arm64-move-bp-hardening-to-check_and_switch_context.patch
queue-4.15/arm-arm64-kvm-advertise-smccc-v1.1.patch
queue-4.15/arm64-move-post_ttbr_update_workaround-to-c-code.patch
queue-4.15/firmware-psci-expose-psci-conduit.patch
queue-4.15/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-high-priority-synchronous-exceptions.patch
queue-4.15/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch
queue-4.15/firmware-psci-expose-smccc-version-through-psci_ops.patch
queue-4.15/arm64-implement-branch-predictor-hardening-for-affected-cortex-a-cpus.patch
queue-4.15/arm-arm64-kvm-add-psci_version-helper.patch
queue-4.15/arm64-kill-psci_get_version-as-a-variant-2-workaround.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-suspicious-interrupts-from-el0.patch
queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
queue-4.15/arm64-add-arm_smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm-arm64-kvm-turn-kvm_psci_version-into-a-static-inline.patch
queue-4.15/arm-arm64-kvm-implement-psci-1.0-support.patch
queue-4.15/arm64-kvm-add-smccc_arch_workaround_1-fast-handling.patch
queue-4.15/arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm-arm64-smccc-implement-smccc-v1.1-inline-primitive.patch
queue-4.15/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch
queue-4.15/arm64-kvm-make-psci_version-a-fast-path.patch
queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch
queue-4.15/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch
queue-4.15/arm-arm64-kvm-consolidate-the-psci-include-files.patch
queue-4.15/arm64-add-skeleton-to-harden-the-branch-predictor-against-aliasing-attacks.patch
queue-4.15/arm-arm64-kvm-add-smccc-accessors-to-psci-code.patch
queue-4.15/arm64-kvm-use-per-cpu-vector-when-bp-hardening-is-enabled.patch
queue-4.15/arm64-kvm-increment-pc-after-handling-an-smc-trap.patch