kernel.git/arch/arm64/kvm, branch linux-4.19.y

KVM: arm64: Allow AArch32 PSTATE.M to be restored as System mode

2024-06-16T11:23:44Z

commit dfe6d190f38fc5df5ff2614b463a5195a399c885 upstream. It appears that we don't allow a vcpu to be restored in AArch32 System mode, as we *never* included it in the list of valid modes. Just add it to the list of allowed modes. Fixes: 0d854a60b1d7 ("arm64: KVM: enable initialization of a 32bit vcpu") Cc: stable@vger.kernel.org Acked-by: Oliver Upton Link: https://lore.kernel.org/r/20240524141956.1450304-3-maz@kernel.org Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman

KVM: arm64: limit PMU version to PMUv3 for ARMv8.1

2023-12-08T07:43:23Z

commit c854188ea01062f5a5fd7f05658feb1863774eaa upstream. We currently expose the PMU version of the host to the guest via emulation of the DFR0_EL1 and AA64DFR0_EL1 debug feature registers. However many of the features offered beyond PMUv3 for 8.1 are not supported in KVM. Examples of this include support for the PMMIR registers (added in PMUv3 for ARMv8.4) and 64-bit event counters added in (PMUv3 for ARMv8.5). Let's trap the Debug Feature Registers in order to limit PMUVer/PerfMon in the Debug Feature Registers to PMUv3 for ARMv8.1 to avoid unexpected behaviour. Both ID_AA64DFR0.PMUVer and ID_DFR0.PerfMon follow the "Alternative ID scheme used for the Performance Monitors Extension version" where 0xF means an IMPLEMENTATION DEFINED PMU is implemented, and values 0x0-0xE are treated as with an unsigned field (with 0x0 meaning no PMU is present). As we don't expect to expose an IMPLEMENTATION DEFINED PMU, and our cap is below 0xF, we can treat these fields as unsigned when applying the cap. Signed-off-by: Andrew Murray Reviewed-by: Suzuki K Poulose [Mark: make field names consistent, use perfmon cap] Signed-off-by: Mark Rutland Signed-off-by: Will Deacon [yuzenghui@huawei.com: adjust the context in read_id_reg()] Signed-off-by: Zenghui Yu Signed-off-by: Greg Kroah-Hartman

arm64: KVM: Fix system register enumeration

2023-04-20T10:04:41Z

commit 5d8d4af24460d079ecdb190254b14b528add1228 upstream. The introduction of the SVE registers to userspace started with a refactoring of the way we expose any register via the ONE_REG interface. Unfortunately, this change doesn't exactly behave as expected if the number of registers is non-zero and consider everything to be an error. The visible result is that QEMU barfs very early when creating vcpus. Make sure we only exit early in case there is an actual error, rather than a positive number of registers... Fixes: be25bbb392fa ("KVM: arm64: Factor out core register ID enumeration") Signed-off-by: Marc Zyngier Signed-off-by: Takahiro Itazuri Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Filter out invalid core register IDs in KVM_GET_REG_LIST

2023-04-20T10:04:41Z

commit df205b5c63281e4f32caac22adda18fd68795e80 upstream. Since commit d26c25a9d19b ("arm64: KVM: Tighten guest core register access from userspace"), KVM_{GET,SET}_ONE_REG rejects register IDs that do not correspond to a single underlying architectural register. KVM_GET_REG_LIST was not changed to match however: instead, it simply yields a list of 32-bit register IDs that together cover the whole kvm_regs struct. This means that if userspace tries to use the resulting list of IDs directly to drive calls to KVM_*_ONE_REG, some of those calls will now fail. This was not the intention. Instead, iterating KVM_*_ONE_REG over the list of IDs returned by KVM_GET_REG_LIST should be guaranteed to work. This patch fixes the problem by splitting validate_core_offset() into a backend core_reg_size_from_offset() which does all of the work except for checking that the size field in the register ID matches, and kvm_arm_copy_reg_indices() and num_core_regs() are converted to use this to enumerate the valid offsets. kvm_arm_copy_reg_indices() now also sets the register ID size field appropriately based on the value returned, so the register ID supplied to userspace is fully qualified for use with the register access ioctls. Cc: stable@vger.kernel.org Fixes: d26c25a9d19b ("arm64: KVM: Tighten guest core register access from userspace") Signed-off-by: Dave Martin Reviewed-by: Andrew Jones Tested-by: Andrew Jones Signed-off-by: Marc Zyngier Signed-off-by: Takahiro Itazuri Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Factor out core register ID enumeration

2023-04-20T10:04:41Z

commit be25bbb392fad3a721d6d21b78639b60612b5439 upstream. In preparation for adding logic to filter out some KVM_REG_ARM_CORE registers from the KVM_GET_REG_LIST output, this patch factors out the core register enumeration into a separate function and rebuilds num_core_regs() on top of it. This may be a little more expensive (depending on how good a job the compiler does of specialising the code), but KVM_GET_REG_LIST is not a hot path. This will make it easier to consolidate ID filtering code in one place. No functional change. Signed-off-by: Dave Martin Reviewed-by: Julien Thierry Tested-by: zhang.lei Signed-off-by: Marc Zyngier Signed-off-by: Takahiro Itazuri Signed-off-by: Greg Kroah-Hartman

arm64: Use the clearbhb instruction in mitigations

2022-03-23T08:10:43Z

commit 228a26b912287934789023b4132ba76065d9491c upstream. Future CPUs may implement a clearbhb instruction that is sufficient to mitigate SpectreBHB. CPUs that implement this instruction, but not CSV2.3 must be affected by Spectre-BHB. Add support to use this instruction as the BHB mitigation on CPUs that support it. The instruction is in the hint space, so it will be treated by a NOP as older CPUs. Reviewed-by: Russell King (Oracle) Reviewed-by: Catalin Marinas [ modified for stable: Use a KVM vector template instead of alternatives ] Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman

arm64: add ID_AA64ISAR2_EL1 sys register

2022-03-23T08:10:43Z

commit 9e45365f1469ef2b934f9d035975dbc9ad352116 upstream. This is a new ID register, introduced in 8.7. Signed-off-by: Joey Gouly Cc: Will Deacon Cc: Marc Zyngier Cc: James Morse Cc: Alexandru Elisei Cc: Suzuki K Poulose Cc: Reiji Watanabe Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20211210165432.8106-3-joey.gouly@arm.com Signed-off-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman

arm64: Mitigate spectre style branch history side channels

2022-03-23T08:10:43Z

commit 558c303c9734af5a813739cd284879227f7297d2 upstream. Speculation attacks against some high-performance processors can make use of branch history to influence future speculation. When taking an exception from user-space, a sequence of branches or a firmware call overwrites or invalidates the branch history. The sequence of branches is added to the vectors, and should appear before the first indirect branch. For systems using KPTI the sequence is added to the kpti trampoline where it has a free register as the exit from the trampoline is via a 'ret'. For systems not using KPTI, the same register tricks are used to free up a register in the vectors. For the firmware call, arch-workaround-3 clobbers 4 registers, so there is no choice but to save them to the EL1 stack. This only happens for entry from EL0, so if we take an exception due to the stack access, it will not become re-entrant. For KVM, the existing branch-predictor-hardening vectors are used. When a spectre version of these vectors is in use, the firmware call is sufficient to mitigate against Spectre-BHB. For the non-spectre versions, the sequence of branches is added to the indirect vector. Reviewed-by: Catalin Marinas Cc: # # # Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Add templates for BHB mitigation sequences

2022-03-23T08:10:43Z

KVM writes the Spectre-v2 mitigation template at the beginning of each vector when a CPU requires a specific sequence to run. Because the template is copied, it can not be modified by the alternatives at runtime. As the KVM template code is intertwined with the bp-hardening callbacks, all templates must have a bp-hardening callback. Add templates for calling ARCH_WORKAROUND_3 and one for each value of K in the brancy-loop. Identify these sequences by a new parameter template_start, and add a copy of install_bp_hardening_cb() that is able to install them. Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman

arm64: Add percpu vectors for EL1

2022-03-23T08:10:43Z

commit bd09128d16fac3c34b80bd6a29088ac632e8ce09 upstream. The Spectre-BHB workaround adds a firmware call to the vectors. This is needed on some CPUs, but not others. To avoid the unaffected CPU in a big/little pair from making the firmware call, create per cpu vectors. The per-cpu vectors only apply when returning from EL0. Systems using KPTI can use the canonical 'full-fat' vectors directly at EL1, the trampoline exit code will switch to this_cpu_vector on exit to EL0. Systems not using KPTI should always use this_cpu_vector. this_cpu_vector will point at a vector in tramp_vecs or __bp_harden_el1_vectors, depending on whether KPTI is in use. Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman