Otherwise the host can spend too long traversing an rmap chain, which happens under a spinlock.
Cc: [email protected] Signed-off-by: Marcelo Tosatti <[email protected]> Index: kvm/arch/x86/kvm/mmu.c =================================================================== --- kvm.orig/arch/x86/kvm/mmu.c +++ kvm/arch/x86/kvm/mmu.c @@ -502,16 +502,20 @@ static unsigned long *gfn_to_rmap(struct * * If rmapp bit zero is one, (then rmap & ~1) points to a struct kvm_rmap_desc * containing more mappings. + * + * Returns the number of rmap entries before the spte was added or zero if + * the spte was not added. + * */ -static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn, int lpage) +static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn, int lpage) { struct kvm_mmu_page *sp; struct kvm_rmap_desc *desc; unsigned long *rmapp; - int i; + int i, count = 0; if (!is_rmap_spte(*spte)) - return; + return count; gfn = unalias_gfn(vcpu->kvm, gfn); sp = page_header(__pa(spte)); sp->gfns[spte - sp->spt] = gfn; @@ -528,8 +532,10 @@ static void rmap_add(struct kvm_vcpu *vc } else { rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte); desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul); - while (desc->sptes[RMAP_EXT-1] && desc->more) + while (desc->sptes[RMAP_EXT-1] && desc->more) { desc = desc->more; + count += RMAP_EXT; + } if (desc->sptes[RMAP_EXT-1]) { desc->more = mmu_alloc_rmap_desc(vcpu); desc = desc->more; @@ -538,6 +544,7 @@ static void rmap_add(struct kvm_vcpu *vc ; desc->sptes[i] = spte; } + return count; } static void rmap_desc_remove_entry(unsigned long *rmapp, @@ -767,6 +774,19 @@ static int kvm_age_rmapp(struct kvm *kvm return young; } +#define RMAP_RECYCLE_THRESHOLD 1000 + +static void rmap_recycle(struct kvm_vcpu *vcpu, gfn_t gfn, int lpage) +{ + unsigned long *rmapp; + + gfn = unalias_gfn(vcpu->kvm, gfn); + rmapp = gfn_to_rmap(vcpu->kvm, gfn, lpage); + + kvm_unmap_rmapp(vcpu->kvm, rmapp); + kvm_flush_remote_tlbs(vcpu->kvm); +} + int kvm_age_hva(struct kvm *kvm, unsigned long hva) { return kvm_handle_hva(kvm, hva, kvm_age_rmapp); @@ -1753,6 +1773,7 @@ static void mmu_set_spte(struct kvm_vcpu { int was_rmapped = 0; int was_writeble = is_writeble_pte(*sptep); + int rmap_count; pgprintk("%s: spte %llx access %x write_fault %d" " user_fault %d gfn %lx\n", @@ -1794,9 +1815,11 @@ static void mmu_set_spte(struct kvm_vcpu page_header_update_slot(vcpu->kvm, sptep, gfn); if (!was_rmapped) { - rmap_add(vcpu, sptep, gfn, largepage); + rmap_count = rmap_add(vcpu, sptep, gfn, largepage); if (!is_rmap_spte(*sptep)) kvm_release_pfn_clean(pfn); + if (rmap_count > RMAP_RECYCLE_THRESHOLD) + rmap_recycle(vcpu, gfn, largepage); } else { if (was_writeble) kvm_release_pfn_dirty(pfn); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
