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KVM: x86/mmu: Grab nx_lpage_splits as an unsigned long before division

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Snapshot kvm->stats.nx_lpage_splits into a local unsigned long to avoid
64-bit division on 32-bit kernels.  Casting to an unsigned long is safe
because the maximum number of shadow pages, n_max_mmu_pages, is also an
unsigned long, i.e. KVM will start recycling shadow pages before the
number of splits can exceed a 32-bit value.

  ERROR: modpost: "__udivdi3" [arch/x86/kvm/kvm.ko] undefined!

Fixes: 7ee093d4f3f5 ("KVM: switch per-VM stats to u64")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210615162905.2132937-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2021-06-15 09:29:05 -07:00
committed by Paolo Bonzini
parent bca66dbcd2
commit ade74e1433
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kvm/mmu/mmu.c
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@@ -6043,6 +6043,7 @@ static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel
static void kvm_recover_nx_lpages(struct kvm *kvm)
{
unsigned long nx_lpage_splits = kvm->stat.nx_lpage_splits;
int rcu_idx;
struct kvm_mmu_page *sp;
unsigned int ratio;
@@ -6054,7 +6055,7 @@ static void kvm_recover_nx_lpages(struct kvm *kvm)
write_lock(&kvm->mmu_lock);
ratio = READ_ONCE(nx_huge_pages_recovery_ratio);
to_zap = ratio ? DIV_ROUND_UP(kvm->stat.nx_lpage_splits, ratio) : 0;
to_zap = ratio ? DIV_ROUND_UP(nx_lpage_splits, ratio) : 0;
for ( ; to_zap; --to_zap) {
if (list_empty(&kvm->arch.lpage_disallowed_mmu_pages))
break;