| Message ID | 20220329031924.619453-1-reijiw@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: arm64: mixed-width check should be skipped for uninitialized vCPUs | expand |
On Mon, 28 Mar 2022 20:19:22 -0700, Reiji Watanabe wrote: > KVM allows userspace to configure either all EL1 32bit or 64bit vCPUs > for a guest. At vCPU reset, vcpu_allowed_register_width() checks > if the vcpu's register width is consistent with all other vCPUs'. > Since the checking is done even against vCPUs that are not initialized > (KVM_ARM_VCPU_INIT has not been done) yet, the uninitialized vCPUs > are erroneously treated as 64bit vCPU, which causes the function to > incorrectly detect a mixed-width VM. > > [...] Applied to fixes, thanks! [1/2] KVM: arm64: mixed-width check should be skipped for uninitialized vCPUs commit: 26bf74bd9f6ff0f1545b4f0c92a37c232d076014 [2/2] KVM: arm64: selftests: Introduce vcpu_width_config commit: 2f5d27e6cf14efe652748bad89ee529ed5a5d577 Note that I have somewhat tweaked the first patch to my own liking. Cheers, M.
KVM allows userspace to configure either all EL1 32bit or 64bit vCPUs for a guest. At vCPU reset, vcpu_allowed_register_width() checks if the vcpu's register width is consistent with all other vCPUs'. Since the checking is done even against vCPUs that are not initialized (KVM_ARM_VCPU_INIT has not been done) yet, the uninitialized vCPUs are erroneously treated as 64bit vCPU, which causes the function to incorrectly detect a mixed-width VM. This series will fix this problem by introducing a new VM flag that indicates the guest needs to be configured with all 32bit or 64bit vCPUs and checking vcpu's register width against the new flag at the vcpu's KVM_ARM_VCPU_INIT (instead of against other vCPUs' register width). Patch-1 introduces KVM_ARCH_FLAG_EL1_32BIT and KVM_ARCH_FLAG_REG_WIDTH_CONFIGURED bits for kvm->arch.flags and uses them to check vcpu's register width to fix the problem. Patch-2 introduces a selftest that can test non-mixed-width vCPUs (all 64bit vCPUs or all 32bit vcPUs) can be configured, and mixed-width vCPUs cannot be configured. The series is based on kvmarm/fixes at: commit 8872d9b3e35a ("KVM: arm64: Drop unneeded minor version check from PSCI v1.x handler") v6: - Fix typo and minor nits in the selftests [Oliver] v5: https://lore.kernel.org/all/20220321050804.2701035-1-reijiw@google.com/ - Rebase to kvmarm/next (and drop the patch-1 "KVM: arm64: Generalise VM features into a set of flags") - Use kernel-doc style comments for kvm_set_vm_width() [Oliver] - Change kvm_set_vm_width() to use if/else instead of a ternary operator for KVM_ARCH_FLAG_EL1_32BIT check [Oliver] v4: https://lore.kernel.org/all/20220314061959.3349716-1-reijiw@google.com/ - Use different implementation of vcpu_el1_is_32bit() depending on the context. [Marc] - Rename kvm_register_width_check_or_init() to kvm_set_vm_width(), and call it from kvm_rest_vcpu() instead of from kvm_vcpu_set_target() - Remove vcpu_allowed_register_width(), and does the same checking in kvm_set_vm_width() instead. v3: https://lore.kernel.org/all/20220303035408.3708241-1-reijiw@google.com/ - Introduced 'flags' to kvm_arch, and use bits of the flags for a set of booleans for VM feature. - Changed 'el1_reg_width' to two bits of 'flags' of kvm_arch. v2: https://lore.kernel.org/all/20220118041923.3384602-1-reijiw@google.com/ - Introduced 'el1_reg_width' for kvm_arch and use it to check vcpu's register width against the flag at the vcpu's KVM_ARM_VCPU_INIT. v1: https://lore.kernel.org/all/20220110054042.1079932-1-reijiw@google.com/ [1] https://lore.kernel.org/all/20210715163159.1480168-2-maz@kernel.org/ Reiji Watanabe (2): KVM: arm64: mixed-width check should be skipped for uninitialized vCPUs KVM: arm64: selftests: Introduce vcpu_width_config arch/arm64/include/asm/kvm_emulate.h | 27 ++-- arch/arm64/include/asm/kvm_host.h | 10 ++ arch/arm64/kvm/reset.c | 65 ++++++---- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/aarch64/vcpu_width_config.c | 122 ++++++++++++++++++ 6 files changed, 196 insertions(+), 30 deletions(-) create mode 100644 tools/testing/selftests/kvm/aarch64/vcpu_width_config.c