From: Christoffer Dall <christoffer.dall@arm.com> To: kvmarm@lists.cs.columbia.edu Cc: "Daniel P. Berrangé" <berrange@redhat.com>, "Marc Zyngier" <maz@kernel.org>, "Stefan Hajnoczi" <stefanha@redhat.com>, "Heinrich Schuchardt" <xypron.glpk@gmx.de>, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 0/2] Improve handling of stage 2 aborts without instruction decode Date: Fri, 11 Oct 2019 13:07:04 +0200 [thread overview] Message-ID: <20191011110709.2764-1-christoffer.dall@arm.com> (raw) When a guest accesses memory outside the memory slots, KVM usually bounces the access back to userspace with KVM_EXIT_MMIO. However, on arm/arm64 systems, certain load/store instructions did not provide decoding info for the hypervisor to emulate the instruction, and in this case KVM has rather rudely returned -ENOSYS and printed a not overly helpful error message: load/store instruction decoding not implemented This patch series improves the error message and allows userspace to be notified of this event instead of receiving -ENOSYS, and also allows userspace to ask KVM to inject an external abort to the guest, which it can use for any memory access that it either cannot handle. One remaining case which this patch set does not address is if the guest accesses an in-kernel emulated device, such as the VGIC, but using a load/store instruction which doesn't provide decode info. With these patches, this will return to userspace for it to handle, but there's no way for userspace to return the decoding information to KVM and have KVM complete the access to the in-kernel emulated device. I have no plans to address this limitation. Changes since v2: - Cleanup inconsistent use of has_ in patch 2 and allow injecting SError and external abort simultaenously with a single call to set VCPU events. Changes since v1: - Rebased on v5.4-rc2 - Fixed some documentation and coding nit in review of v1 Christoffer Dall (2): KVM: arm/arm64: Allow reporting non-ISV data aborts to userspace KVM: arm/arm64: Allow user injection of external data aborts Documentation/virt/kvm/api.txt | 55 +++++++++++++++++++++++++++- arch/arm/include/asm/kvm_arm.h | 1 + arch/arm/include/asm/kvm_emulate.h | 5 +++ arch/arm/include/asm/kvm_host.h | 8 ++++ arch/arm/include/uapi/asm/kvm.h | 3 +- arch/arm/kvm/guest.c | 10 +++++ arch/arm64/include/asm/kvm_emulate.h | 5 +++ arch/arm64/include/asm/kvm_host.h | 8 ++++ arch/arm64/include/uapi/asm/kvm.h | 3 +- arch/arm64/kvm/guest.c | 10 +++++ arch/arm64/kvm/inject_fault.c | 4 +- include/uapi/linux/kvm.h | 8 ++++ virt/kvm/arm/arm.c | 22 +++++++++++ virt/kvm/arm/mmio.c | 9 ++++- 14 files changed, 145 insertions(+), 6 deletions(-) -- 2.18.0 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
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From: Christoffer Dall <christoffer.dall@arm.com> To: kvmarm@lists.cs.columbia.edu Cc: "Peter Maydell" <peter.maydell@linaro.org>, "Daniel P. Berrangé" <berrange@redhat.com>, "Suzuki K Poulose" <suzuki.poulose@arm.com>, "Marc Zyngier" <maz@kernel.org>, "Christoffer Dall" <christoffer.dall@arm.com>, "James Morse" <james.morse@arm.com>, "Julien Thierry" <julien.thierry.kdev@gmail.com>, "Stefan Hajnoczi" <stefanha@redhat.com>, "Heinrich Schuchardt" <xypron.glpk@gmx.de>, "Alexander Graf" <graf@amazon.com>, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 0/2] Improve handling of stage 2 aborts without instruction decode Date: Fri, 11 Oct 2019 13:07:04 +0200 [thread overview] Message-ID: <20191011110709.2764-1-christoffer.dall@arm.com> (raw) When a guest accesses memory outside the memory slots, KVM usually bounces the access back to userspace with KVM_EXIT_MMIO. However, on arm/arm64 systems, certain load/store instructions did not provide decoding info for the hypervisor to emulate the instruction, and in this case KVM has rather rudely returned -ENOSYS and printed a not overly helpful error message: load/store instruction decoding not implemented This patch series improves the error message and allows userspace to be notified of this event instead of receiving -ENOSYS, and also allows userspace to ask KVM to inject an external abort to the guest, which it can use for any memory access that it either cannot handle. One remaining case which this patch set does not address is if the guest accesses an in-kernel emulated device, such as the VGIC, but using a load/store instruction which doesn't provide decode info. With these patches, this will return to userspace for it to handle, but there's no way for userspace to return the decoding information to KVM and have KVM complete the access to the in-kernel emulated device. I have no plans to address this limitation. Changes since v2: - Cleanup inconsistent use of has_ in patch 2 and allow injecting SError and external abort simultaenously with a single call to set VCPU events. Changes since v1: - Rebased on v5.4-rc2 - Fixed some documentation and coding nit in review of v1 Christoffer Dall (2): KVM: arm/arm64: Allow reporting non-ISV data aborts to userspace KVM: arm/arm64: Allow user injection of external data aborts Documentation/virt/kvm/api.txt | 55 +++++++++++++++++++++++++++- arch/arm/include/asm/kvm_arm.h | 1 + arch/arm/include/asm/kvm_emulate.h | 5 +++ arch/arm/include/asm/kvm_host.h | 8 ++++ arch/arm/include/uapi/asm/kvm.h | 3 +- arch/arm/kvm/guest.c | 10 +++++ arch/arm64/include/asm/kvm_emulate.h | 5 +++ arch/arm64/include/asm/kvm_host.h | 8 ++++ arch/arm64/include/uapi/asm/kvm.h | 3 +- arch/arm64/kvm/guest.c | 10 +++++ arch/arm64/kvm/inject_fault.c | 4 +- include/uapi/linux/kvm.h | 8 ++++ virt/kvm/arm/arm.c | 22 +++++++++++ virt/kvm/arm/mmio.c | 9 ++++- 14 files changed, 145 insertions(+), 6 deletions(-) -- 2.18.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-10-11 11:07 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-11 11:07 Christoffer Dall [this message] 2019-10-11 11:07 ` [PATCH v3 0/2] Improve handling of stage 2 aborts without instruction decode Christoffer Dall 2019-10-11 11:07 ` [PATCH v3 1/2] KVM: arm/arm64: Allow reporting non-ISV data aborts to userspace Christoffer Dall 2019-10-11 11:07 ` Christoffer Dall 2019-10-11 11:07 ` [PATCH v3 2/2] KVM: arm/arm64: Allow user injection of external data aborts Christoffer Dall 2019-10-11 11:07 ` Christoffer Dall 2019-10-21 20:21 ` Alexander Graf 2019-10-21 20:21 ` Alexander Graf 2019-10-11 11:07 ` [kvmtool v3 3/5] update headers: Update the KVM headers for new Arm fault reporting features Christoffer Dall 2019-10-11 11:07 ` Christoffer Dall 2019-10-11 11:07 ` [kvmtool v3 4/5] arm: Handle exits from undecoded load/store instructions Christoffer Dall 2019-10-11 11:07 ` Christoffer Dall 2019-10-11 11:07 ` [kvmtool v3 5/5] arm: Inject external data aborts when accessing holes in the memory map Christoffer Dall 2019-10-11 11:07 ` Christoffer Dall 2019-10-20 10:25 ` [PATCH v3 0/2] Improve handling of stage 2 aborts without instruction decode Marc Zyngier 2019-10-20 10:25 ` Marc Zyngier 2019-10-21 13:37 ` Christoffer Dall 2019-10-21 13:37 ` Christoffer Dall 2019-10-21 13:59 ` Marc Zyngier 2019-10-21 13:59 ` Marc Zyngier
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