linux-dev/arch/arm64/kvm/guest.c, branch linus/master

KVM: arm64: Setup a framework for hypercall bitmap firmware registers

2022-05-03T20:30:19Z

KVM regularly introduces new hypercall services to the guests without any consent from the userspace. This means, the guests can observe hypercall services in and out as they migrate across various host kernel versions. This could be a major problem if the guest discovered a hypercall, started using it, and after getting migrated to an older kernel realizes that it's no longer available. Depending on how the guest handles the change, there's a potential chance that the guest would just panic. As a result, there's a need for the userspace to elect the services that it wishes the guest to discover. It can elect these services based on the kernels spread across its (migration) fleet. To remedy this, extend the existing firmware pseudo-registers, such as KVM_REG_ARM_PSCI_VERSION, but by creating a new COPROC register space for all the hypercall services available. These firmware registers are categorized based on the service call owners, but unlike the existing firmware pseudo-registers, they hold the features supported in the form of a bitmap. During the VM initialization, the registers are set to upper-limit of the features supported by the corresponding registers. It's expected that the VMMs discover the features provided by each register via GET_ONE_REG, and write back the desired values using SET_ONE_REG. KVM allows this modification only until the VM has started. Some of the standard features are not mapped to any bits of the registers. But since they can recreate the original problem of making it available without userspace's consent, they need to be explicitly added to the case-list in kvm_hvc_call_default_allowed(). Any function-id that's not enabled via the bitmap, or not listed in kvm_hvc_call_default_allowed, will be returned as SMCCC_RET_NOT_SUPPORTED to the guest. Older userspace code can simply ignore the feature and the hypercall services will be exposed unconditionally to the guests, thus ensuring backward compatibility. In this patch, the framework adds the register only for ARM's standard secure services (owner value 4). Currently, this includes support only for ARM True Random Number Generator (TRNG) service, with bit-0 of the register representing mandatory features of v1.0. Other services are momentarily added in the upcoming patches. Signed-off-by: Raghavendra Rao Ananta Reviewed-by: Gavin Shan [maz: reduced the scope of some helpers, tidy-up bitmap max values, dropped error-only fast path] Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220502233853.1233742-3-rananta@google.com

KVM: arm64: Factor out firmware register handling from psci.c

2022-05-03T13:48:54Z

Common hypercall firmware register handing is currently employed by psci.c. Since the upcoming patches add more of these registers, it's better to move the generic handling to hypercall.c for a cleaner presentation. While we are at it, collect all the firmware registers under fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and kvm_arm_copy_fw_reg_indices() in a generic way. Also, define KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead. No functional change intended. Signed-off-by: Raghavendra Rao Ananta Reviewed-by: Oliver Upton Reviewed-by: Gavin Shan [maz: fixed KVM_REG_FEATURE_LEVEL_MASK] Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220502233853.1233742-2-rananta@google.com

KVM: arm64: fix typos in comments

2022-03-18T14:04:15Z

Various spelling mistakes in comments. Detected with the help of Coccinelle. Signed-off-by: Julia Lawall Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220318103729.157574-24-Julia.Lawall@inria.fr

KVM: arm64: Change the return type of kvm_vcpu_preferred_target()

2021-11-08T10:48:47Z

kvm_vcpu_preferred_target() always return 0 because kvm_target_cpu() never returns a negative error code. Signed-off-by: YueHaibing Reviewed-by: Alexandru Elisei Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211105011500.16280-1-yuehaibing@huawei.com

Merge tag 'kvmarm-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2021-09-06T10:34:48Z

KVM/arm64 updates for 5.15 - Page ownership tracking between host EL1 and EL2 - Rely on userspace page tables to create large stage-2 mappings - Fix incompatibility between pKVM and kmemleak - Fix the PMU reset state, and improve the performance of the virtual PMU - Move over to the generic KVM entry code - Address PSCI reset issues w.r.t. save/restore - Preliminary rework for the upcoming pKVM fixed feature - A bunch of MM cleanups - a vGIC fix for timer spurious interrupts - Various cleanups

KVM: stats: Support linear and logarithmic histogram statistics

2021-08-20T20:06:32Z

Add new types of KVM stats, linear and logarithmic histogram. Histogram are very useful for observing the value distribution of time or size related stats. Signed-off-by: Jing Zhang Message-Id: <20210802165633.1866976-2-jingzhangos@google.com> Signed-off-by: Paolo Bonzini

Merge branch kvm-arm64/generic-entry into kvmarm-master/next

2021-08-20T11:23:09Z

Switch KVM/arm64 to the generic entry code, courtesy of Oliver Upton * kvm-arm64/generic-entry: KVM: arm64: Use generic KVM xfer to guest work function entry: KVM: Allow use of generic KVM entry w/o full generic support KVM: arm64: Record number of signal exits as a vCPU stat Signed-off-by: Marc Zyngier

KVM: arm64: Record number of signal exits as a vCPU stat

2021-08-19T10:19:41Z

Most other architectures that implement KVM record a statistic indicating the number of times a vCPU has exited due to a pending signal. Add support for that stat to arm64. Reviewed-by: Jing Zhang Signed-off-by: Oliver Upton Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210802192809.1851010-2-oupton@google.com

KVM: arm64: Drop check_kvm_target_cpu() based percpu probe

2021-08-18T08:26:07Z

kvm_target_cpu() never returns a negative error code, so check_kvm_target() would never have 'ret' filled with a negative error code. Hence the percpu probe via check_kvm_target_cpu() does not make sense as its never going to find an unsupported CPU, forcing kvm_arch_init() to exit early. Hence lets just drop this percpu probe (and also check_kvm_target_cpu()) altogether. While here, this also changes kvm_target_cpu() return type to a u32, making it explicit that an error code will not be returned from this function. Cc: Marc Zyngier Cc: James Morse Cc: Alexandru Elisei Cc: Suzuki K Poulose Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Cc: kvmarm@lists.cs.columbia.edu Cc: linux-kernel@vger.kernel.org Acked-by: Will Deacon Signed-off-by: Anshuman Khandual Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/1628744994-16623-5-git-send-email-anshuman.khandual@arm.com

Merge tag 'kvmarm-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2021-06-25T15:24:24Z

KVM/arm64 updates for v5.14. - Add MTE support in guests, complete with tag save/restore interface - Reduce the impact of CMOs by moving them in the page-table code - Allow device block mappings at stage-2 - Reduce the footprint of the vmemmap in protected mode - Support the vGIC on dumb systems such as the Apple M1 - Add selftest infrastructure to support multiple configuration and apply that to PMU/non-PMU setups - Add selftests for the debug architecture - The usual crop of PMU fixes