[PATCH v2 00/25] arm64: KVM: Mediate access to GICv3 sysregs at EL2

Marc Zyngier
2017-06-01T10:20:52Z

Some systems have less than perfect GICv3 implementations, leading to
all kind of ugly issues (guest hanging, host dying). In order to allow
some level of diagnostic, and in some cases implement workarounds,
this series enables the trapping of both Group-0, Group-1 and Common
sysregs. Mediating the access at EL2 allows some form of sanity
checking that the HW is sometimes sorely lacking.

Instead of fully emulating a GICv3 CPU interface, we still use the
existing HW (list registers, AP registers, VMCR...), which allows the
code to be independent from the rest of the KVM code, and to cope with
partial trapping.

Of course, trapping has a cost, which is why this must be either
enabled on the command line, or selected by another cpu capability
(see Cavium erratum 30115). A quick test on an A57-based platform
shows a 25% hit when repeatedly banging on the trapped registers,
while normal workloads do not seem to suffer noticeably from such
trapping (hackbench variance is in the usual noise, despite being very
IPI happy).

This has been tested on a dual socket Thundex-X and a Freescale LS-2085a.

I've taken the liberty to rebase David Daney's initial Cavium erratum
30115 workaround on top of this series, and included it here as a
typical use case.

- From v1:
* Fix bug in DIR handling which would have performed a deactivation even
when EOImode==0
* Some minor cleanups and clarifications.
* All the initial fixes have already been merged.
* Rebased on 4.12-rc3.

David Daney (2):
arm64: Add MIDR values for Cavium cn83XX SoCs
arm64: Add workaround for Cavium Thunder erratum 30115

Marc Zyngier (23):
arm64: Add a facility to turn an ESR syndrome into a sysreg encoding
KVM: arm/arm64: vgic-v3: Add accessors for the ICH_APxRn_EL2 registers
KVM: arm64: Make kvm_condition_valid32() accessible from EL2
KVM: arm64: vgic-v3: Add hook to handle guest GICv3 sysreg accesses at
EL2
KVM: arm64: vgic-v3: Add ICV_BPR1_EL1 handler
KVM: arm64: vgic-v3: Add ICV_IGRPEN1_EL1 handler
KVM: arm64: vgic-v3: Add ICV_IAR1_EL1 handler
KVM: arm64: vgic-v3: Add ICV_EOIR1_EL1 handler
KVM: arm64: vgic-v3: Add ICV_AP1Rn_EL1 handler
KVM: arm64: vgic-v3: Add ICV_HPPIR1_EL1 handler
KVM: arm64: vgic-v3: Enable trapping of Group-1 system registers
KVM: arm64: Enable GICv3 Group-1 sysreg trapping via command-line
KVM: arm64: vgic-v3: Add ICV_BPR0_EL1 handler
KVM: arm64: vgic-v3: Add ICV_IGNREN0_EL1 handler
KVM: arm64: vgic-v3: Add misc Group-0 handlers
KVM: arm64: vgic-v3: Enable trapping of Group-0 system registers
KVM: arm64: Enable GICv3 Group-0 sysreg trapping via command-line
KVM: arm64: vgic-v3: Add ICV_DIR_EL1 handler
KVM: arm64: vgic-v3: Add ICV_RPR_EL1 handler
KVM: arm64: vgic-v3: Add ICV_CTLR_EL1 handler
KVM: arm64: vgic-v3: Add ICV_PMR_EL1 handler
KVM: arm64: Enable GICv3 common sysreg trapping via command-line
KVM: arm64: vgic-v3: Log which GICv3 system registers are trapped

Documentation/arm64/silicon-errata.txt | 1 +
arch/arm64/Kconfig | 11 +
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/cputype.h | 2 +
arch/arm64/include/asm/esr.h | 24 +
arch/arm64/include/asm/kvm_hyp.h | 1 +
arch/arm64/include/asm/sysreg.h | 9 +
arch/arm64/kernel/cpu_errata.c | 21 +
arch/arm64/kvm/hyp/switch.c | 14 +
include/kvm/arm_vgic.h | 1 +
include/linux/irqchip/arm-gic-v3.h | 6 +
virt/kvm/arm/aarch32.c | 2 +-
virt/kvm/arm/hyp/vgic-v3-sr.c | 803 ++++++++++++++++++++++++++++++++-
virt/kvm/arm/vgic/vgic-v3.c | 45 ++
14 files changed, 925 insertions(+), 18 deletions(-)

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2.11.0