path: root/arch
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authorMark Rutland <mark.rutland@arm.com>2017-02-20 12:30:12 +0000
committerMarc Zyngier <marc.zyngier@arm.com>2017-03-07 14:50:46 +0000
commitba4dd156eabdca93501d92a980ba27fa5f4bbd27 (patch)
treef70d911b1351cf97ed51c10e49d0523f32a6dd61 /arch
parentarm: KVM: Survive unknown traps from guests (diff)
arm64: KVM: Survive unknown traps from guests
Currently we BUG() if we see an ESR_EL2.EC value we don't recognise. As configurable disables/enables are added to the architecture (controlled by RES1/RES0 bits respectively), with associated synchronous exceptions, it may be possible for a guest to trigger exceptions with classes that we don't recognise. While we can't service these exceptions in a manner useful to the guest, we can avoid bringing down the host. Per ARM DDI 0487A.k_iss10775, page D7-1937, EC values within the range 0x00 - 0x2c are reserved for future use with synchronous exceptions, and EC values within the range 0x2d - 0x3f may be used for either synchronous or asynchronous exceptions. The patch makes KVM handle any unknown EC by injecting an UNDEFINED exception into the guest, with a corresponding (ratelimited) warning in the host dmesg. We could later improve on this with with a new (opt-in) exit to the host userspace. Cc: Dave Martin <dave.martin@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to '')
1 files changed, 12 insertions, 7 deletions
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 1bfe30dfbfe7..fa1b18e364fc 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -135,7 +135,19 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run)
return ret;
+static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
+ u32 hsr = kvm_vcpu_get_hsr(vcpu);
+ kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n",
+ hsr, esr_get_class_string(hsr));
+ kvm_inject_undefined(vcpu);
+ return 1;
static exit_handle_fn arm_exit_handlers[] = {
+ [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
[ESR_ELx_EC_WFx] = kvm_handle_wfx,
[ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
[ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
@@ -162,13 +174,6 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
u32 hsr = kvm_vcpu_get_hsr(vcpu);
u8 hsr_ec = ESR_ELx_EC(hsr);
- if (hsr_ec >= ARRAY_SIZE(arm_exit_handlers) ||
- !arm_exit_handlers[hsr_ec]) {
- kvm_err("Unknown exception class: hsr: %#08x -- %s\n",
- hsr, esr_get_class_string(hsr));
- BUG();
- }
return arm_exit_handlers[hsr_ec];