kernel/linux.git/arch/arm64/kvm, branch v6.3

Merge tag 'kvmarm-fixes-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2023-04-21T23:19:02+00:00

KVM/arm64 fixes for 6.3, part #4 - Plug a buffer overflow due to the use of the user-provided register width for firmware regs. Outright reject accesses where the user register width does not match the kernel representation. - Protect non-atomic RMW operations on vCPU flags against preemption, as an update to the flags by an intervening preemption could be lost.

KVM: arm64: Fix buffer overflow in kvm_arm_set_fw_reg()

2023-04-19T15:22:37+00:00

The KVM_REG_SIZE() comes from the ioctl and it can be a power of two between 0-32768 but if it is more than sizeof(long) this will corrupt memory. Fixes: 99adb567632b ("KVM: arm/arm64: Add save/restore support for firmware workaround state") Signed-off-by: Dan Carpenter Reviewed-by: Steven Price Reviewed-by: Eric Auger Reviewed-by: Marc Zyngier Link: https://lore.kernel.org/r/4efbab8c-640f-43b2-8ac6-6d68e08280fe@kili.mountain Signed-off-by: Oliver Upton

Merge tag 'kvmarm-fixes-6.3-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2023-04-06T17:34:19+00:00

KVM/arm64 fixes for 6.3, part #3 - Ensure the guest PMU context is restored before the first KVM_RUN, fixing an issue where EL0 event counting is broken after vCPU save/restore - Actually initialize ID_AA64PFR0_EL1.{CSV2,CSV3} based on the sanitized, system-wide values for protected VMs

KVM: arm64: Advertise ID_AA64PFR0_EL1.CSV2/3 to protected VMs

2023-04-04T15:52:06+00:00

The existing pKVM code attempts to advertise CSV2/3 using values initialized to 0, but never set. To advertise CSV2/3 to protected guests, pass the CSV2/3 values to hyp when initializing hyp's view of guests' ID_AA64PFR0_EL1. Similar to non-protected KVM, these are system-wide, rather than per cpu, for simplicity. Fixes: 6c30bfb18d0b ("KVM: arm64: Add handlers for protected VM System Registers") Signed-off-by: Fuad Tabba Link: https://lore.kernel.org/r/20230404152321.413064-1-tabba@google.com Signed-off-by: Oliver Upton

KVM: PPC: Make KVM_CAP_IRQFD_RESAMPLE platform dependent

2023-03-31T15:19:05+00:00

When introduced, IRQFD resampling worked on POWER8 with XICS. However KVM on POWER9 has never implemented it - the compatibility mode code ("XICS-on-XIVE") misses the kvm_notify_acked_irq() call and the native XIVE mode does not handle INTx in KVM at all. This moved the capability support advertising to platforms and stops advertising it on XIVE, i.e. POWER9 and later. Signed-off-by: Alexey Kardashevskiy Acked-by: Anup Patel Acked-by: Nicholas Piggin Message-Id: <20220504074807.3616813-1-aik@ozlabs.ru> Signed-off-by: Paolo Bonzini

KVM: arm64: PMU: Restore the guest's EL0 event counting after migration

2023-03-30T06:14:43+00:00

Currently, with VHE, KVM enables the EL0 event counting for the guest on vcpu_load() or KVM enables it as a part of the PMU register emulation process, when needed. However, in the migration case (with VHE), the same handling is lacking, as vPMU register values that were restored by userspace haven't been propagated yet (the PMU events haven't been created) at the vcpu load-time on the first KVM_RUN (kvm_vcpu_pmu_restore_guest() called from vcpu_load() on the first KVM_RUN won't do anything as events_{guest,host} of kvm_pmu_events are still zero). So, with VHE, enable the guest's EL0 event counting on the first KVM_RUN (after the migration) when needed. More specifically, have kvm_pmu_handle_pmcr() call kvm_vcpu_pmu_restore_guest() so that kvm_pmu_handle_pmcr() on the first KVM_RUN can take care of it. Fixes: d0c94c49792c ("KVM: arm64: Restore PMU configuration on first run") Cc: stable@vger.kernel.org Reviewed-by: Marc Zyngier Signed-off-by: Reiji Watanabe Link: https://lore.kernel.org/r/20230329023944.2488484-1-reijiw@google.com Signed-off-by: Oliver Upton

KVM: arm64: Check for kvm_vma_mte_allowed in the critical section

2023-03-16T23:42:56+00:00

On page fault, we find about the VMA that backs the page fault early on, and quickly release the mmap_read_lock. However, using the VMA pointer after the critical section is pretty dangerous, as a teardown may happen in the meantime and the VMA be long gone. Move the sampling of the MTE permission early, and NULL-ify the VMA pointer after that, just to be on the safe side. Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230316174546.3777507-3-maz@kernel.org Signed-off-by: Oliver Upton

KVM: arm64: Disable interrupts while walking userspace PTs

2023-03-16T23:42:56+00:00

We walk the userspace PTs to discover what mapping size was used there. However, this can race against the userspace tables being freed, and we end-up in the weeds. Thankfully, the mm code is being generous and will IPI us when doing so. So let's implement our part of the bargain and disable interrupts around the walk. This ensures that nothing terrible happens during that time. We still need to handle the removal of the page tables before the walk. For that, allow get_user_mapping_size() to return an error, and make sure this error can be propagated all the way to the the exit handler. Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230316174546.3777507-2-maz@kernel.org Signed-off-by: Oliver Upton

KVM: arm64: Retry fault if vma_lookup() results become invalid

2023-03-14T16:47:10+00:00

Read mmu_invalidate_seq before dropping the mmap_lock so that KVM can detect if the results of vma_lookup() (e.g. vma_shift) become stale before it acquires kvm->mmu_lock. This fixes a theoretical bug where a VMA could be changed by userspace after vma_lookup() and before KVM reads the mmu_invalidate_seq, causing KVM to install page table entries based on a (possibly) no-longer-valid vma_shift. Re-order the MMU cache top-up to earlier in user_mem_abort() so that it is not done after KVM has read mmu_invalidate_seq (i.e. so as to avoid inducing spurious fault retries). This bug has existed since KVM/ARM's inception. It's unlikely that any sane userspace currently modifies VMAs in such a way as to trigger this race. And even with directed testing I was unable to reproduce it. But a sufficiently motivated host userspace might be able to exploit this race. Fixes: 94f8e6418d39 ("KVM: ARM: Handle guest faults in KVM") Cc: stable@vger.kernel.org Reported-by: Sean Christopherson Signed-off-by: David Matlack Reviewed-by: Marc Zyngier Link: https://lore.kernel.org/r/20230313235454.2964067-1-dmatlack@google.com Signed-off-by: Oliver Upton

KVM: arm64: PMU: Don't save PMCR_EL0.{C,P} for the vCPU

2023-03-13T18:05:57+00:00

Presently, when a guest writes 1 to PMCR_EL0.{C,P}, which is WO/RAZ, KVM saves the register value, including these bits. When userspace reads the register using KVM_GET_ONE_REG, KVM returns the saved register value as it is (the saved value might have these bits set). This could result in userspace setting these bits on the destination during migration. Consequently, KVM may end up resetting the vPMU counter registers (PMCCNTR_EL0 and/or PMEVCNTR_EL0) to zero on the first KVM_RUN after migration. Fix this by not saving those bits when a guest writes 1 to those bits. Fixes: ab9468340d2b ("arm64: KVM: Add access handler for PMCR register") Cc: stable@vger.kernel.org Reviewed-by: Marc Zyngier Signed-off-by: Reiji Watanabe Link: https://lore.kernel.org/r/20230313033234.1475987-1-reijiw@google.com Signed-off-by: Oliver Upton