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| author | Mark Rutland <mark.rutland@arm.com> | 2017-02-20 15:30:12 +0300 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2017-03-07 17:50:46 +0300 |
| commit | ba4dd156eabdca93501d92a980ba27fa5f4bbd27 (patch) | |
| tree | f70d911b1351cf97ed51c10e49d0523f32a6dd61 /arch/arm64 | |
| parent | f050fe7a9164945dd1c28be05bf00e8cfb082ccf (diff) | |
| download | linux-ba4dd156eabdca93501d92a980ba27fa5f4bbd27.tar.xz | |
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 'arch/arm64')
| -rw-r--r-- | arch/arm64/kvm/handle_exit.c | 19 |
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]; } |