[PATCH 00/19] Handle guest-generated SErrors/Aborts

Marc Zyngier
2016-09-06T13:01:58Z

A little known "feature" of giving guest access to real memory mapped
HW is that it could trigger asynchronous aborts (SError on ARMv8) if
the guest accesses it in a non-conventional way (and depending on how
HW and firmware have been integrated). So far, KVM lacks any support
to handle this gracefully.

This series introduces a set of mechanisms to catch such a fault and
deliver a vSError (or Virtual Abort for 32bit) to the offending vcpu.

These aborts can either trigger at EL1 (whilst the guest is running),
or at EL2 (during the handling of an exit). The first case is pretty
easy to handle (use the ad-hoc vectors on arm64, or decode the EA bit
on arm), but the second one is a bit more fiddly, as we need to ensure
that the exception is pending by the time we unmask it. This is
achived by using some heavy DSBs on the hot path, with the following
caveats:

- I've only been able to trigger the EL2 handling on A57 (Seatle,
Juno).
- I've measured a 40/50 cycles hit on Juno (A57), but I haven't
measured the impact on bigger systems

The last patch of this series adds a missing feature to the
GICV-proxying series, delivering a vSError to a guest that performed
an illegal access to the GIC.

Patches on top of current kvmarm/queue + the GICV przying series.

Marc Zyngier (19):
arm64: KVM: Rename HCR_VA to HCR_VSE
arm64: KVM: Preserve pending vSError in world switch
arm64: KVM: Add Virtual Abort injection helper
arm64: KVM: Add exception code to report EL1 asynchronous aborts
arm64: KVM: Add EL1 async abort handler
arm64: KVM: Route asynchronous aborts
arm64: KVM: Allow an exit code to be tagged with an SError
arm64: KVM: Inject a Virtual SError if it was pending
arm64: KVM: Handle async aborts delivered while at EL2
arm: KVM: Preserve pending Virtual Abort in world switch
arm: KVM: Add Virtual Abort injection helper
arm: KVM: Add HYP async abort handler
arm: KVM: Allow an exit code to be tagged with a Virtual Abort
arm: KVM: Handle async aborts delivered while at HYP
arm: KVM: Inject a Virtual Abort if it was pending
arm: KVM: Drop unreachable HYP abort handlers
arm/arm64: KVM: Inject virtual abort when guest exits on external
abort
arm/arm64: KVM: Remove external abort test from MMIO handling
arm64: KVM: Inject a vSerror if detecting a bad GICV access at EL2

arch/arm/include/asm/kvm_asm.h | 4 +++
arch/arm/include/asm/kvm_emulate.h | 1 +
arch/arm/kvm/emulate.c | 12 +++++++++
arch/arm/kvm/handle_exit.c | 49 ++++++++++++++++--------------------
arch/arm/kvm/hyp/entry.S | 31 +++++++++++++++++++++++
arch/arm/kvm/hyp/hyp-entry.S | 16 +++++++++++-
arch/arm/kvm/hyp/switch.c | 9 +++++++
arch/arm/kvm/mmio.c | 6 -----
arch/arm/kvm/mmu.c | 5 ++++
arch/arm64/include/asm/kvm_arm.h | 4 +--
arch/arm64/include/asm/kvm_asm.h | 9 +++++--
arch/arm64/include/asm/kvm_emulate.h | 1 +
arch/arm64/include/asm/kvm_hyp.h | 2 +-
arch/arm64/kvm/handle_exit.c | 23 +++++++++++++++++
arch/arm64/kvm/hyp/entry.S | 33 +++++++++++++++++++++++-
arch/arm64/kvm/hyp/hyp-entry.S | 36 ++++++++++++++++++++++----
arch/arm64/kvm/hyp/switch.c | 33 +++++++++++++++++++++---
arch/arm64/kvm/inject_fault.c | 12 +++++++++
virt/kvm/arm/hyp/vgic-v2-sr.c | 21 ++++++++++++----
19 files changed, 254 insertions(+), 53 deletions(-)

--
2.1.4