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KVM: riscv: Rely on common MMU notifier locking

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The common KVM invalidation paths call kvm_unmap_gfn_range() with
mmu_lock already held for write.

For the standard MMU notifier path, the call chain is:

  kvm_mmu_notifier_invalidate_range_start()
    kvm_handle_hva_range()
      kvm_unmap_gfn_range()

kvm_mmu_notifier_invalidate_range_start() leaves range.lockless clear.
kvm_handle_hva_range() therefore takes KVM_MMU_LOCK(kvm) before invoking
the handler.

The guest_memfd path has the same locking contract:

  __kvm_gmem_invalidate_begin()
    kvm_mmu_unmap_gfn_range()
      kvm_unmap_gfn_range()

__kvm_gmem_invalidate_begin() explicitly takes KVM_MMU_LOCK(kvm) before
calling kvm_mmu_unmap_gfn_range().

So remove the local trylock and make the common locking contract explicit
with lockdep_assert_held_write() like x86.

Signed-off-by: Jinyu Tang <tjytimi@163.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260517153427.94889-2-tjytimi@163.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Jinyu Tang 2026-05-17 23:34:23 +08:00 committed by Anup Patel
parent c70faabb6d
commit 9090ba2e7c
1 changed files with 2 additions and 7 deletions
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9
arch/riscv/kvm/mmu.c
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@ -245,22 +245,17 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
{
struct kvm_gstage gstage;
bool mmu_locked;
bool flush;
if (!kvm->arch.pgd)
return false;
kvm_riscv_gstage_init(&gstage, kvm);
mmu_locked = spin_trylock(&kvm->mmu_lock);
lockdep_assert_held_write(&kvm->mmu_lock);
kvm_riscv_gstage_init(&gstage, kvm);
flush = kvm_riscv_gstage_unmap_range(&gstage, range->start << PAGE_SHIFT,
(range->end - range->start) << PAGE_SHIFT,
range->may_block);
if (mmu_locked)
spin_unlock(&kvm->mmu_lock);
if (flush)
kvm_flush_remote_tlbs_range(kvm, range->start,
range->end - range->start);