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KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes

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Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Zeng Chi 2026-09-21 18:24:42 +08:00 committed by Sean Christopherson
parent 382e5d514b
commit 119e9db233
1 changed files with 3 additions and 2 deletions
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5
virt/kvm/kvm_main.c
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@ -2593,9 +2593,10 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
/*
* Reserve memory ahead of time to avoid having to deal with failures
* partway through setting the new attributes.
* partway through setting the new attributes. Storing NULL never
* allocates, so no reservations are needed when clearing.
*/
for (i = start; i < end; i++) {
for (i = start; entry && i < end; i++) {
r = xa_reserve(&kvm->mem_attr_array, i, GFP_KERNEL_ACCOUNT);
if (r)
goto out_unlock;