Hi Marcelo,
On Jul 10, 2014, at 3:12 AM, mtosatti@xxxxxxxxxx wrote:
> struct kvm_vcpu_arch {
> /*
> * rip and regs accesses must go through
> @@ -392,6 +402,9 @@
> struct kvm_mmu_memory_cache mmu_page_cache;
> struct kvm_mmu_memory_cache mmu_page_header_cache;
>
> + struct list_head pinned_mmu_pages;
> + atomic_t nr_pinned_ranges;
> +
I’m not sure per-cpu pinned list is a good idea, since currently all vcpu are using the same
page table, the per-list can not reduce lock-contention, why not make it be global to vm
instead?
> struct fpu guest_fpu;
> u64 xcr0;
> u64 guest_supported_xcr0;
> Index: kvm.pinned-sptes/arch/x86/kvm/mmu.c
> ===================================================================
> --- kvm.pinned-sptes.orig/arch/x86/kvm/mmu.c 2014-07-09 12:05:34.837161264 -0300
> +++ kvm.pinned-sptes/arch/x86/kvm/mmu.c 2014-07-09 12:09:21.856684314 -0300
> @@ -148,6 +148,9 @@
>
> #define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
> #define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
> +#define SPTE_PINNED (1ULL << (PT64_SECOND_AVAIL_BITS_SHIFT))
> +
> +#define SPTE_PINNED_BIT PT64_SECOND_AVAIL_BITS_SHIFT
>
> #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
>
> @@ -327,6 +330,11 @@
> return pte & PT_PRESENT_MASK && !is_mmio_spte(pte);
> }
>
> +static int is_pinned_spte(u64 spte)
> +{
> + return spte & SPTE_PINNED && is_shadow_present_pte(spte);
> +}
> +
> static int is_large_pte(u64 pte)
> {
> return pte & PT_PAGE_SIZE_MASK;
> @@ -1176,6 +1184,16 @@
> kvm_flush_remote_tlbs(vcpu->kvm);
> }
>
> +static bool vcpu_has_pinned(struct kvm_vcpu *vcpu)
> +{
> + return atomic_read(&vcpu->arch.nr_pinned_ranges);
> +}
> +
> +static void mmu_reload_pinned_vcpus(struct kvm *kvm)
> +{
> + make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD, &vcpu_has_pinned);
> +}
> +
> /*
> * Write-protect on the specified @sptep, @pt_protect indicates whether
> * spte write-protection is caused by protecting shadow page table.
> @@ -1268,7 +1286,8 @@
> }
>
> static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
> - struct kvm_memory_slot *slot, unsigned long data)
> + struct kvm_memory_slot *slot, unsigned long data,
> + bool age)
> {
> u64 *sptep;
> struct rmap_iterator iter;
> @@ -1278,6 +1297,14 @@
> BUG_ON(!(*sptep & PT_PRESENT_MASK));
> rmap_printk("kvm_rmap_unmap_hva: spte %p %llx\n", sptep, *sptep);
>
> + if (is_pinned_spte(*sptep)) {
> + /* don't nuke pinned sptes if page aging: return
> + * young=yes instead.
> + */
> + if (age)
> + return 1;
> + mmu_reload_pinned_vcpus(kvm);
> + }
> drop_spte(kvm, step);
This has a window between zapping spte and re-pin spte, so guest will fail
at this time.
> need_tlb_flush = 1;
> }
> @@ -1286,7 +1313,8 @@
> }
>
> static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
> - struct kvm_memory_slot *slot, unsigned long data)
> + struct kvm_memory_slot *slot, unsigned long data,
> + bool age)
> {
> u64 *sptep;
> struct rmap_iterator iter;
> @@ -1304,6 +1332,9 @@
>
> need_flush = 1;
>
> + if (is_pinned_spte(*sptep))
> + mmu_reload_pinned_vcpus(kvm);
> +
> if (pte_write(*ptep)) {
> drop_spte(kvm, sptep);
> sptep = rmap_get_first(*rmapp, &iter);
> @@ -1334,7 +1365,8 @@
> int (*handler)(struct kvm *kvm,
> unsigned long *rmapp,
> struct kvm_memory_slot *slot,
> - unsigned long data))
> + unsigned long data,
> + bool age))
> {
> int j;
> int ret = 0;
> @@ -1374,7 +1406,7 @@
> rmapp = __gfn_to_rmap(gfn_start, j, memslot);
>
> for (; idx <= idx_end; ++idx)
> - ret |= handler(kvm, rmapp++, memslot, data);
> + ret |= handler(kvm, rmapp++, memslot, data, false);
> }
> }
>
> @@ -1385,7 +1417,8 @@
> unsigned long data,
> int (*handler)(struct kvm *kvm, unsigned long *rmapp,
> struct kvm_memory_slot *slot,
> - unsigned long data))
> + unsigned long data,
> + bool age))
> {
> return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler);
> }
> @@ -1406,7 +1439,8 @@
> }
>
> static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
> - struct kvm_memory_slot *slot, unsigned long data)
> + struct kvm_memory_slot *slot, unsigned long data,
> + bool age)
> {
> u64 *sptep;
> struct rmap_iterator uninitialized_var(iter);
> @@ -1421,7 +1455,7 @@
> * out actively used pages or breaking up actively used hugepages.
> */
> if (!shadow_accessed_mask) {
> - young = kvm_unmap_rmapp(kvm, rmapp, slot, data);
> + young = kvm_unmap_rmapp(kvm, rmapp, slot, data, true);
> goto out;
> }
>
> @@ -1442,7 +1476,8 @@
> }
>
> static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
> - struct kvm_memory_slot *slot, unsigned long data)
> + struct kvm_memory_slot *slot, unsigned long data,
> + bool age)
> {
> u64 *sptep;
> struct rmap_iterator iter;
> @@ -1480,7 +1515,7 @@
>
> rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
>
> - kvm_unmap_rmapp(vcpu->kvm, rmapp, NULL, 0);
> + kvm_unmap_rmapp(vcpu->kvm, rmapp, NULL, 0, false);
> kvm_flush_remote_tlbs(vcpu->kvm);
> }
>
> @@ -2753,7 +2788,8 @@
> }
>
> static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
> - pfn_t pfn, unsigned access, int *ret_val)
> + pfn_t pfn, unsigned access, int *ret_val,
> + bool pin)
> {
> bool ret = true;
>
> @@ -2763,8 +2799,14 @@
> goto exit;
> }
>
> - if (unlikely(is_noslot_pfn(pfn)))
> + if (unlikely(is_noslot_pfn(pfn))) {
> + /* pinned sptes must point to RAM */
> + if (unlikely(pin)) {
> + *ret_val = -EFAULT;
> + goto exit;
> + }
> vcpu_cache_mmio_info(vcpu, gva, gfn, access);
> + }
>
> ret = false;
> exit:
> @@ -2818,7 +2860,7 @@
> * - false: let the real page fault path to fix it.
> */
> static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
> - u32 error_code)
> + u32 error_code, bool pin)
> {
> struct kvm_shadow_walk_iterator iterator;
> struct kvm_mmu_page *sp;
> @@ -2828,6 +2870,9 @@
> if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
> return false;
>
> + if (pin)
> + return false;
> +
> if (!page_fault_can_be_fast(error_code))
> return false;
>
> @@ -2895,9 +2940,71 @@
> }
>
> static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
> - gva_t gva, pfn_t *pfn, bool write, bool *writable);
> + gva_t gva, pfn_t *pfn, bool write, bool *writable,
> + bool pin);
> static void make_mmu_pages_available(struct kvm_vcpu *vcpu);
>
> +
> +static int get_sptep_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes[4])
> +
> +{
> + struct kvm_shadow_walk_iterator iterator;
> + int nr_sptes = 0;
> +
> + if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
> + return nr_sptes;
> +
> + for_each_shadow_entry(vcpu, addr, iterator) {
> + sptes[iterator.level-1] = iterator.sptep;
> + nr_sptes++;
> + if (!is_shadow_present_pte(*iterator.sptep))
> + break;
> + }
> +
> + return nr_sptes;
> +}
> +
> +static bool __direct_pin_sptes(struct kvm_vcpu *vcpu, gfn_t gfn, bool pin)
> +{
> + u64 *sptes[4];
> + int r, i, level;
> +
> + r = get_sptep_hierarchy(vcpu, gfn << PAGE_SHIFT, sptes);
> + if (!r)
> + return false;
> +
> + level = 5 - r;
> + if (!is_last_spte(*sptes[level-1], level))
> + return false;
> + if (!is_shadow_present_pte(*sptes[level-1]))
> + return false;
> +
> + for (i = 0; i < r; i++) {
> + u64 *sptep = sptes[3-i];
> + struct kvm_mmu_page *sp = page_header(__pa(sptep));
> +
> + if (pin) {
> + sp->pinned = true;
> + set_bit(SPTE_PINNED_BIT, (unsigned long *)sptep);
> + } else {
> + sp->pinned = false;
> + clear_bit(SPTE_PINNED_BIT, (unsigned long *)sptep);
> + }
> + }
> +
> + return true;
> +}
> +
> +static bool direct_pin_sptes(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + return __direct_pin_sptes(vcpu, gfn, true);
> +}
> +
> +static bool direct_unpin_sptes(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + return __direct_pin_sptes(vcpu, gfn, false);
> +}
> +
I guess we can reuse the infrastructure which marks/clears unsync spte
to pin/unpind pages that can omit lot of code in this patch.
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