lkml.org 
[lkml]   [2021]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] KVM: x86/mmu: Grab nx_lpage_splits as an unsigned long before division
From
Date
On 15/06/21 18:29, Sean Christopherson wrote:
> 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>
> ---
> arch/x86/kvm/mmu/mmu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 720ceb0a1f5c..7d3e57678d34 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -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;
>

Queued, thanks.

Paolo

\
 
 \ /
  Last update: 2021-06-17 19:11    [W:0.044 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site