[PATCH 4/6] KVM: PPC: Book3S HV Nested: Change nested guest lookup to use idr
Fabiano Rosas
farosas at linux.ibm.com
Tue Jan 25 09:14:48 AEDT 2022
Nicholas Piggin <npiggin at gmail.com> writes:
> This removes the fixed sized kvm->arch.nested_guests array.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
Reviewed-by: Fabiano Rosas <farosas at linux.ibm.com>
> arch/powerpc/include/asm/kvm_host.h | 3 +-
> arch/powerpc/kvm/book3s_hv_nested.c | 110 +++++++++++++++-------------
> 2 files changed, 59 insertions(+), 54 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index d9bf60bf0816..5fd0564e5c94 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -326,8 +326,7 @@ struct kvm_arch {
> struct list_head uvmem_pfns;
> struct mutex mmu_setup_lock; /* nests inside vcpu mutexes */
> u64 l1_ptcr;
> - int max_nested_lpid;
> - struct kvm_nested_guest *nested_guests[KVM_MAX_NESTED_GUESTS];
> + struct idr kvm_nested_guest_idr;
> /* This array can grow quite large, keep it at the end */
> struct kvmppc_vcore *vcores[KVM_MAX_VCORES];
> #endif
> diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
> index 9d373f8963ee..1eff969b095c 100644
> --- a/arch/powerpc/kvm/book3s_hv_nested.c
> +++ b/arch/powerpc/kvm/book3s_hv_nested.c
> @@ -521,11 +521,6 @@ static void kvmhv_set_nested_ptbl(struct kvm_nested_guest *gp)
> kvmhv_set_ptbl_entry(gp->shadow_lpid, dw0, gp->process_table);
> }
>
> -void kvmhv_vm_nested_init(struct kvm *kvm)
> -{
> - kvm->arch.max_nested_lpid = -1;
> -}
> -
> /*
> * Handle the H_SET_PARTITION_TABLE hcall.
> * r4 = guest real address of partition table + log_2(size) - 12
> @@ -660,6 +655,35 @@ static void kvmhv_update_ptbl_cache(struct kvm_nested_guest *gp)
> kvmhv_set_nested_ptbl(gp);
> }
>
> +void kvmhv_vm_nested_init(struct kvm *kvm)
> +{
> + idr_init(&kvm->arch.kvm_nested_guest_idr);
> +}
> +
> +static struct kvm_nested_guest *__find_nested(struct kvm *kvm, int lpid)
> +{
> + return idr_find(&kvm->arch.kvm_nested_guest_idr, lpid);
> +}
> +
> +static bool __prealloc_nested(struct kvm *kvm, int lpid)
> +{
> + if (idr_alloc(&kvm->arch.kvm_nested_guest_idr,
> + NULL, lpid, lpid + 1, GFP_KERNEL) != lpid)
> + return false;
> + return true;
> +}
> +
> +static void __add_nested(struct kvm *kvm, int lpid, struct kvm_nested_guest *gp)
> +{
> + if (idr_replace(&kvm->arch.kvm_nested_guest_idr, gp, lpid))
> + WARN_ON(1);
> +}
> +
> +static void __remove_nested(struct kvm *kvm, int lpid)
> +{
> + idr_remove(&kvm->arch.kvm_nested_guest_idr, lpid);
> +}
> +
> static struct kvm_nested_guest *kvmhv_alloc_nested(struct kvm *kvm, unsigned int lpid)
> {
> struct kvm_nested_guest *gp;
> @@ -720,13 +744,8 @@ static void kvmhv_remove_nested(struct kvm_nested_guest *gp)
> long ref;
>
> spin_lock(&kvm->mmu_lock);
> - if (gp == kvm->arch.nested_guests[lpid]) {
> - kvm->arch.nested_guests[lpid] = NULL;
> - if (lpid == kvm->arch.max_nested_lpid) {
> - while (--lpid >= 0 && !kvm->arch.nested_guests[lpid])
> - ;
> - kvm->arch.max_nested_lpid = lpid;
> - }
> + if (gp == __find_nested(kvm, lpid)) {
> + __remove_nested(kvm, lpid);
> --gp->refcnt;
> }
> ref = gp->refcnt;
> @@ -743,24 +762,22 @@ static void kvmhv_remove_nested(struct kvm_nested_guest *gp)
> */
> void kvmhv_release_all_nested(struct kvm *kvm)
> {
> - int i;
> + int lpid;
> struct kvm_nested_guest *gp;
> struct kvm_nested_guest *freelist = NULL;
> struct kvm_memory_slot *memslot;
> int srcu_idx, bkt;
>
> spin_lock(&kvm->mmu_lock);
> - for (i = 0; i <= kvm->arch.max_nested_lpid; i++) {
> - gp = kvm->arch.nested_guests[i];
> - if (!gp)
> - continue;
> - kvm->arch.nested_guests[i] = NULL;
> + idr_for_each_entry(&kvm->arch.kvm_nested_guest_idr, gp, lpid) {
> + __remove_nested(kvm, lpid);
> if (--gp->refcnt == 0) {
> gp->next = freelist;
> freelist = gp;
> }
> }
> - kvm->arch.max_nested_lpid = -1;
> + idr_destroy(&kvm->arch.kvm_nested_guest_idr);
> + /* idr is empty and may be reused at this point */
> spin_unlock(&kvm->mmu_lock);
> while ((gp = freelist) != NULL) {
> freelist = gp->next;
> @@ -797,7 +814,7 @@ struct kvm_nested_guest *kvmhv_get_nested(struct kvm *kvm, int l1_lpid,
> return NULL;
>
> spin_lock(&kvm->mmu_lock);
> - gp = kvm->arch.nested_guests[l1_lpid];
> + gp = __find_nested(kvm, l1_lpid);
> if (gp)
> ++gp->refcnt;
> spin_unlock(&kvm->mmu_lock);
> @@ -808,17 +825,19 @@ struct kvm_nested_guest *kvmhv_get_nested(struct kvm *kvm, int l1_lpid,
> newgp = kvmhv_alloc_nested(kvm, l1_lpid);
> if (!newgp)
> return NULL;
> +
> + if (!__prealloc_nested(kvm, l1_lpid)) {
> + kvmhv_release_nested(newgp);
> + return NULL;
> + }
> +
> spin_lock(&kvm->mmu_lock);
> - if (kvm->arch.nested_guests[l1_lpid]) {
> - /* someone else beat us to it */
> - gp = kvm->arch.nested_guests[l1_lpid];
> - } else {
> - kvm->arch.nested_guests[l1_lpid] = newgp;
> + gp = __find_nested(kvm, l1_lpid);
> + if (!gp) {
> + __add_nested(kvm, l1_lpid, newgp);
> ++newgp->refcnt;
> gp = newgp;
> newgp = NULL;
> - if (l1_lpid > kvm->arch.max_nested_lpid)
> - kvm->arch.max_nested_lpid = l1_lpid;
> }
> ++gp->refcnt;
> spin_unlock(&kvm->mmu_lock);
> @@ -841,20 +860,13 @@ void kvmhv_put_nested(struct kvm_nested_guest *gp)
> kvmhv_release_nested(gp);
> }
>
> -static struct kvm_nested_guest *kvmhv_find_nested(struct kvm *kvm, int lpid)
> -{
> - if (lpid > kvm->arch.max_nested_lpid)
> - return NULL;
> - return kvm->arch.nested_guests[lpid];
> -}
> -
> pte_t *find_kvm_nested_guest_pte(struct kvm *kvm, unsigned long lpid,
> unsigned long ea, unsigned *hshift)
> {
> struct kvm_nested_guest *gp;
> pte_t *pte;
>
> - gp = kvmhv_find_nested(kvm, lpid);
> + gp = __find_nested(kvm, lpid);
> if (!gp)
> return NULL;
>
> @@ -960,7 +972,7 @@ static void kvmhv_remove_nest_rmap(struct kvm *kvm, u64 n_rmap,
>
> gpa = n_rmap & RMAP_NESTED_GPA_MASK;
> lpid = (n_rmap & RMAP_NESTED_LPID_MASK) >> RMAP_NESTED_LPID_SHIFT;
> - gp = kvmhv_find_nested(kvm, lpid);
> + gp = __find_nested(kvm, lpid);
> if (!gp)
> return;
>
> @@ -1152,16 +1164,13 @@ static void kvmhv_emulate_tlbie_all_lpid(struct kvm_vcpu *vcpu, int ric)
> {
> struct kvm *kvm = vcpu->kvm;
> struct kvm_nested_guest *gp;
> - int i;
> + int lpid;
>
> spin_lock(&kvm->mmu_lock);
> - for (i = 0; i <= kvm->arch.max_nested_lpid; i++) {
> - gp = kvm->arch.nested_guests[i];
> - if (gp) {
> - spin_unlock(&kvm->mmu_lock);
> - kvmhv_emulate_tlbie_lpid(vcpu, gp, ric);
> - spin_lock(&kvm->mmu_lock);
> - }
> + idr_for_each_entry(&kvm->arch.kvm_nested_guest_idr, gp, lpid) {
> + spin_unlock(&kvm->mmu_lock);
> + kvmhv_emulate_tlbie_lpid(vcpu, gp, ric);
> + spin_lock(&kvm->mmu_lock);
> }
> spin_unlock(&kvm->mmu_lock);
> }
> @@ -1313,7 +1322,7 @@ long do_h_rpt_invalidate_pat(struct kvm_vcpu *vcpu, unsigned long lpid,
> * H_ENTER_NESTED call. Since we can't differentiate this case from
> * the invalid case, we ignore such flush requests and return success.
> */
> - if (!kvmhv_find_nested(vcpu->kvm, lpid))
> + if (!__find_nested(vcpu->kvm, lpid))
> return H_SUCCESS;
>
> /*
> @@ -1657,15 +1666,12 @@ long int kvmhv_nested_page_fault(struct kvm_vcpu *vcpu)
>
> int kvmhv_nested_next_lpid(struct kvm *kvm, int lpid)
> {
> - int ret = -1;
> + int ret = lpid + 1;
>
> spin_lock(&kvm->mmu_lock);
> - while (++lpid <= kvm->arch.max_nested_lpid) {
> - if (kvm->arch.nested_guests[lpid]) {
> - ret = lpid;
> - break;
> - }
> - }
> + if (!idr_get_next(&kvm->arch.kvm_nested_guest_idr, &ret))
> + ret = -1;
> spin_unlock(&kvm->mmu_lock);
> +
> return ret;
> }
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