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| author | Mark Rutland <mark.rutland@arm.com> | 2017-02-20 12:30:11 +0000 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2017-03-07 14:50:45 +0000 |
| commit | f050fe7a9164945dd1c28be05bf00e8cfb082ccf (patch) | |
| tree | a5b6a432b0371828356fd8e56ef71e488e1467a2 /arch/arm | |
| parent | 370a0ec1819990f8e2a93df7cc9c0146980ed45f (diff) | |
| download | linux-f050fe7a9164945dd1c28be05bf00e8cfb082ccf.tar.bz2 | |
arm: KVM: Survive unknown traps from guests
Currently we BUG() if we see a HSR.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 0406C.c, all currently
unallocated HSR EC encodings are reserved, and per ARM DDI
0487A.k_iss10775, page G6-4395, 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/arm')
| -rw-r--r-- | arch/arm/include/asm/kvm_arm.h | 1 | ||||
| -rw-r--r-- | arch/arm/kvm/handle_exit.c | 19 |
2 files changed, 13 insertions, 7 deletions
diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h index e22089fb44dc..a3f0b3d50089 100644 --- a/arch/arm/include/asm/kvm_arm.h +++ b/arch/arm/include/asm/kvm_arm.h @@ -209,6 +209,7 @@ #define HSR_EC_IABT_HYP (0x21) #define HSR_EC_DABT (0x24) #define HSR_EC_DABT_HYP (0x25) +#define HSR_EC_MAX (0x3f) #define HSR_WFI_IS_WFE (_AC(1, UL) << 0) diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c index 4e40d1955e35..96af65a30d78 100644 --- a/arch/arm/kvm/handle_exit.c +++ b/arch/arm/kvm/handle_exit.c @@ -79,7 +79,19 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } +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\n", + hsr); + + kvm_inject_undefined(vcpu); + return 1; +} + static exit_handle_fn arm_exit_handlers[] = { + [0 ... HSR_EC_MAX] = kvm_handle_unknown_ec, [HSR_EC_WFI] = kvm_handle_wfx, [HSR_EC_CP15_32] = kvm_handle_cp15_32, [HSR_EC_CP15_64] = kvm_handle_cp15_64, @@ -98,13 +110,6 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) { u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu); - if (hsr_ec >= ARRAY_SIZE(arm_exit_handlers) || - !arm_exit_handlers[hsr_ec]) { - kvm_err("Unknown exception class: hsr: %#08x\n", - (unsigned int)kvm_vcpu_get_hsr(vcpu)); - BUG(); - } - return arm_exit_handlers[hsr_ec]; } |