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Revert "KVM: arm64: Reschedule as needed when destroying the stage-2 page-tables"

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This reverts commit e9abe311f3.

syzkaller has managed to tease out multiple bugs in this change and
fixing-forward didn't remedy the situation. Considering newly-introduced
memory safety issues the potential for scheduler stalls don't seem that
bad in comparison

Link: https://lore.kernel.org/kvmarm/68c09802.050a0220.3c6139.000d.GAE@google.com/
Message-ID: <20250910180930.3679473-2-oliver.upton@linux.dev>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2025-09-10 11:09:28 -07:00
parent c04f174129
commit fc670ad596
1 changed files with 1 additions and 25 deletions
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26
arch/arm64/kvm/mmu.c
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@ -904,35 +904,11 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type)
return 0;
}
/*
* Assume that @pgt is valid and unlinked from the KVM MMU to free the
* page-table without taking the kvm_mmu_lock and without performing any
* TLB invalidations.
*
* Also, the range of addresses can be large enough to cause need_resched
* warnings, for instance on CONFIG_PREEMPT_NONE kernels. Hence, invoke
* cond_resched() periodically to prevent hogging the CPU for a long time
* and schedule something else, if required.
*/
static void stage2_destroy_range(struct kvm_pgtable *pgt, phys_addr_t addr,
phys_addr_t end)
{
u64 next;
do {
next = stage2_range_addr_end(addr, end);
KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, addr,
next - addr);
if (next != end)
cond_resched();
} while (addr = next, addr != end);
}
static void kvm_stage2_destroy(struct kvm_pgtable *pgt)
{
unsigned int ia_bits = VTCR_EL2_IPA(pgt->mmu->vtcr);
stage2_destroy_range(pgt, 0, BIT(ia_bits));
KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, 0, BIT(ia_bits));
KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt);
}