kernel.git/arch/arm/kvm, branch linux-3.18.y

arm64: KVM: Skip MMIO insn after emulation

2019-02-20T09:09:00Z

[ Upstream commit 0d640732dbebed0f10f18526de21652931f0b2f2 ] When we emulate an MMIO instruction, we advance the CPU state within decode_hsr(), before emulating the instruction effects. Having this logic in decode_hsr() is opaque, and advancing the state before emulation is problematic. It gets in the way of applying consistent single-step logic, and it prevents us from being able to fail an MMIO instruction with a synchronous exception. Clean this up by only advancing the CPU state *after* the effects of the instruction are emulated. Cc: Peter Maydell Reviewed-by: Alex Bennée Reviewed-by: Christoffer Dall Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin

arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm

2018-11-10T15:39:18Z

[ Upstream commit 90f6e150e44a0dc3883110eeb3ab35d1be42b6bb ] We don't hold the mmap_sem while searching for the VMAs when we try to unmap each memslot for a VM. Fix this properly to avoid unexpected results. Fixes: commit 957db105c997 ("arm/arm64: KVM: Introduce stage2_unmap_vm") Cc: stable@vger.kernel.org # v3.19+ Reviewed-by: Christoffer Dall Signed-off-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin

KVM: arm/arm64: Skip updating PMD entry if no change

2018-09-05T07:16:22Z

commit 86658b819cd0a9aa584cd84453ed268a6f013770 upstream. Contention on updating a PMD entry by a large number of vcpus can lead to duplicate work when handling stage 2 page faults. As the page table update follows the break-before-make requirement of the architecture, it can lead to repeated refaults due to clearing the entry and flushing the tlbs. This problem is more likely when - * there are large number of vcpus * the mapping is large block mapping such as when using PMD hugepages (512MB) with 64k pages. Fix this by skipping the page table update if there is no change in the entry being updated. Cc: stable@vger.kernel.org Fixes: ad361f093c1e ("KVM: ARM: Support hugetlbfs backed huge pages") Reviewed-by: Suzuki Poulose Acked-by: Christoffer Dall Signed-off-by: Punit Agrawal Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman

KVM: arm/arm64: Skip updating PTE entry if no change

2018-09-05T07:16:22Z

commit 976d34e2dab10ece5ea8fe7090b7692913f89084 upstream. When there is contention on faulting in a particular page table entry at stage 2, the break-before-make requirement of the architecture can lead to additional refaulting due to TLB invalidation. Avoid this by skipping a page table update if the new value of the PTE matches the previous value. Cc: stable@vger.kernel.org Fixes: d5d8184d35c9 ("KVM: ARM: Memory virtualization setup") Reviewed-by: Suzuki Poulose Acked-by: Christoffer Dall Signed-off-by: Punit Agrawal Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman

arm: KVM: Survive unknown traps from guests

2017-12-16T09:32:29Z

[ Upstream commit f050fe7a9164945dd1c28be05bf00e8cfb082ccf ] Currently we BUG() if we see a HSR.EC value we don't recognise. As configurable disables/enables are added to the architecture (controlled by RES1/RES0 bits respectively), with associated synchronous exceptions, it may be possible for a guest to trigger exceptions with classes that we don't recognise. While we can't service these exceptions in a manner useful to the guest, we can avoid bringing down the host. Per ARM DDI 0406C.c, all currently unallocated HSR EC encodings are reserved, and per ARM DDI 0487A.k_iss10775, page G6-4395, EC values within the range 0x00 - 0x2c are reserved for future use with synchronous exceptions, and EC values within the range 0x2d - 0x3f may be used for either synchronous or asynchronous exceptions. The patch makes KVM handle any unknown EC by injecting an UNDEFINED exception into the guest, with a corresponding (ratelimited) warning in the host dmesg. We could later improve on this with with a new (opt-in) exit to the host userspace. Cc: Dave Martin Cc: Suzuki K Poulose Reviewed-by: Christoffer Dall Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

arm: KVM: Allow unaligned accesses at HYP

2017-06-14T10:54:18Z

commit 33b5c38852b29736f3b472dd095c9a18ec22746f upstream. We currently have the HSCTLR.A bit set, trapping unaligned accesses at HYP, but we're not really prepared to deal with it. Since the rest of the kernel is pretty happy about that, let's follow its example and set HSCTLR.A to zero. Modern CPUs don't really care. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Greg Kroah-Hartman

kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd

2017-04-30T03:49:14Z

commit 8b3405e345b5a098101b0c31b264c812bba045d9 upstream. In kvm_free_stage2_pgd() we don't hold the kvm->mmu_lock while calling unmap_stage2_range() on the entire memory range for the guest. This could cause problems with other callers (e.g, munmap on a memslot) trying to unmap a range. And since we have to unmap the entire Guest memory range holding a spinlock, make sure we yield the lock if necessary, after we unmap each PUD range. Fixes: commit d5d8184d35c9 ("KVM: ARM: Memory virtualization setup") Cc: Paolo Bonzini Cc: Marc Zyngier Cc: Christoffer Dall Cc: Mark Rutland Signed-off-by: Suzuki K Poulose [ Avoid vCPU starvation and lockup detector warnings ] Signed-off-by: Marc Zyngier Signed-off-by: Suzuki K Poulose Signed-off-by: Christoffer Dall Signed-off-by: Greg Kroah-Hartman

arm/arm64: KVM: Take mmap_sem in kvm_arch_prepare_memory_region

2017-04-22T05:15:03Z

commit 72f310481a08db821b614e7b5d00febcc9064b36 upstream. We don't hold the mmap_sem while searching for VMAs (via find_vma), in kvm_arch_prepare_memory_region, which can end up in expected failures. Fixes: commit 8eef91239e57 ("arm/arm64: KVM: map MMIO regions at creation time") Cc: Ard Biesheuvel Cc: Eric Auger Reviewed-by: Christoffer Dall [ Handle dirty page logging failure case ] Signed-off-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman

kvm-arm: Unmap shadow pagetables properly

2016-10-06T02:40:20Z

[ Upstream commit 293f293637b55db4f9f522a5a72514e98a541076 ] On arm/arm64, we depend on the kvm_unmap_hva* callbacks (via mmu_notifiers::invalidate_*) to unmap the stage2 pagetables when the userspace buffer gets unmapped. However, when the Hypervisor process exits without explicit unmap of the guest buffers, the only notifier we get is kvm_arch_flush_shadow_all() (via mmu_notifier::release ) which does nothing on arm. Later this causes us to access pages that were already released [via exit_mmap() -> unmap_vmas()] when we actually get to unmap the stage2 pagetable [via kvm_arch_destroy_vm() -> kvm_free_stage2_pgd()]. This triggers crashes with CONFIG_DEBUG_PAGEALLOC, which unmaps any free'd pages from the linear map. [ 757.644120] Unable to handle kernel paging request at virtual address ffff800661e00000 [ 757.652046] pgd = ffff20000b1a2000 [ 757.655471] [ffff800661e00000] *pgd=00000047fffe3003, *pud=00000047fcd8c003, *pmd=00000047fcc7c003, *pte=00e8004661e00712 [ 757.666492] Internal error: Oops: 96000147 [#3] PREEMPT SMP [ 757.672041] Modules linked in: [ 757.675100] CPU: 7 PID: 3630 Comm: qemu-system-aar Tainted: G D 4.8.0-rc1 #3 [ 757.683240] Hardware name: AppliedMicro X-Gene Mustang Board/X-Gene Mustang Board, BIOS 3.06.15 Aug 19 2016 [ 757.692938] task: ffff80069cdd3580 task.stack: ffff8006adb7c000 [ 757.698840] PC is at __flush_dcache_area+0x1c/0x40 [ 757.703613] LR is at kvm_flush_dcache_pmd+0x60/0x70 [ 757.708469] pc : [] lr : [] pstate: 20000145 ... [ 758.357249] [] __flush_dcache_area+0x1c/0x40 [ 758.363059] [] unmap_stage2_range+0x458/0x5f0 [ 758.368954] [] kvm_free_stage2_pgd+0x34/0x60 [ 758.374761] [] kvm_arch_destroy_vm+0x20/0x68 [ 758.380570] [] kvm_put_kvm+0x210/0x358 [ 758.385860] [] kvm_vm_release+0x2c/0x40 [ 758.391239] [] __fput+0x114/0x2e8 [ 758.396096] [] ____fput+0xc/0x18 [ 758.400869] [] task_work_run+0x108/0x138 [ 758.406332] [] do_exit+0x48c/0x10e8 [ 758.411363] [] do_group_exit+0x6c/0x130 [ 758.416739] [] get_signal+0x284/0xa18 [ 758.421943] [] do_signal+0x158/0x860 [ 758.427060] [] do_notify_resume+0x6c/0x88 [ 758.432608] [] work_pending+0x10/0x14 [ 758.437812] Code: 9ac32042 8b010001 d1000443 8a230000 (d50b7e20) This patch fixes the issue by moving the kvm_free_stage2_pgd() to kvm_arch_flush_shadow_all(). Cc: # 3.9+ Tested-by: Itaru Kitayama Reported-by: Itaru Kitayama Reported-by: James Morse Cc: Marc Zyngier Cc: Catalin Marinas Cc: Christoffer Dall Signed-off-by: Suzuki K Poulose Signed-off-by: Christoffer Dall Signed-off-by: Sasha Levin

KVM: arm/arm64: Stop leaking vcpu pid references

2016-07-12T12:47:14Z

[ Upstream commit 591d215afcc2f94e8e2c69a63c924c044677eb31 ] kvm provides kvm_vcpu_uninit(), which amongst other things, releases the last reference to the struct pid of the task that was last running the vcpu. On arm64 built with CONFIG_DEBUG_KMEMLEAK, starting a guest with kvmtool, then killing it with SIGKILL results (after some considerable time) in: > cat /sys/kernel/debug/kmemleak > unreferenced object 0xffff80007d5ea080 (size 128): > comm "lkvm", pid 2025, jiffies 4294942645 (age 1107.776s) > hex dump (first 32 bytes): > 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [] create_object+0xfc/0x278 > [] kmemleak_alloc+0x34/0x70 > [] kmem_cache_alloc+0x16c/0x1d8 > [] alloc_pid+0x34/0x4d0 > [] copy_process.isra.6+0x79c/0x1338 > [] _do_fork+0x74/0x320 > [] SyS_clone+0x18/0x20 > [] el0_svc_naked+0x24/0x28 > [] 0xffffffffffffffff On x86 kvm_vcpu_uninit() is called on the path from kvm_arch_destroy_vm(), on arm no equivalent call is made. Add the call to kvm_arch_vcpu_free(). Signed-off-by: James Morse Fixes: 749cf76c5a36 ("KVM: ARM: Initial skeleton to compile KVM support") Cc: # 3.10+ Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Sasha Levin