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.
Signed-off-by: Mark Rutland <mark.rutl...@arm.com>
Cc: Christoffer Dall <christoffer.d...@linaro.org>
Cc: Dave Martin <dave.mar...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: Suzuki K Poulose <suzuki.poul...@arm.com>
---
arch/arm64/kvm/handle_exit.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 1bfe30d..fa1b18e 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];
}
--
1.9.1
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