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author | Marc Zyngier <marc.zyngier@arm.com> | 2016-01-29 18:01:28 +0300 |
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committer | Marc Zyngier <marc.zyngier@arm.com> | 2016-02-29 21:34:15 +0300 |
commit | 57c841f131ef295b583365d2fddd6b0d16e82c10 (patch) | |
tree | e015fcf1eccbcc2d01f87762cddb29738e1a3bf8 /arch/arm/kvm | |
parent | 402f352876ba0df574533e59d72fc3e9871f791a (diff) | |
download | linux-57c841f131ef295b583365d2fddd6b0d16e82c10.tar.xz |
arm/arm64: KVM: Handle out-of-RAM cache maintenance as a NOP
So far, our handling of cache maintenance by VA has been pretty
simple: Either the access is in the guest RAM and generates a S2
fault, which results in the page being mapped RW, or we go down
the io_mem_abort() path, and nuke the guest.
The first one is fine, but the second one is extremely weird.
Treating the CM as an I/O is wrong, and nothing in the ARM ARM
indicates that we should generate a fault for something that
cannot end-up in the cache anyway (even if the guest maps it,
it will keep on faulting at stage-2 for emulation).
So let's just skip this instruction, and let the guest get away
with it.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'arch/arm/kvm')
-rw-r--r-- | arch/arm/kvm/mmu.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index aba61fd3697a..c3eb10ea0971 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1431,6 +1431,22 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) } /* + * Check for a cache maintenance operation. Since we + * ended-up here, we know it is outside of any memory + * slot. But we can't find out if that is for a device, + * or if the guest is just being stupid. The only thing + * we know for sure is that this range cannot be cached. + * + * So let's assume that the guest is just being + * cautious, and skip the instruction. + */ + if (kvm_vcpu_dabt_is_cm(vcpu)) { + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); + ret = 1; + goto out_unlock; + } + + /* * The IPA is reported as [MAX:12], so we need to * complement it with the bottom 12 bits from the * faulting VA. This is always 12 bits, irrespective |