On Fri, Sep 21, 2018 at 08:01:48PM +1000, Paul Mackerras wrote:
> From: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
>
> The radix page fault handler accounts for all cases, including just
> needing to insert a pte. This breaks it up into separate functions for
> the two main cases; setting rc and inserting a pte.
>
> This allows us to make the setting of rc and inserting of a pte
> generic for any pgtable, not specific to the one for this guest.
>
> [paulus@xxxxxxxxxx - reduced diffs from previous code]
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_64_mmu_radix.c | 210 +++++++++++++++++++--------------
> 1 file changed, 123 insertions(+), 87 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> index f2976f4..47f2b18 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> @@ -400,8 +400,9 @@ static void kvmppc_unmap_free_pud_entry_table(struct kvm *kvm, pud_t *pud,
> */
> #define PTE_BITS_MUST_MATCH (~(_PAGE_WRITE | _PAGE_DIRTY | _PAGE_ACCESSED))
>
> -static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
> - unsigned int level, unsigned long mmu_seq)
> +static int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
> + unsigned long gpa, unsigned int level,
> + unsigned long mmu_seq)
> {
> pgd_t *pgd;
> pud_t *pud, *new_pud = NULL;
> @@ -410,7 +411,7 @@ static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
> int ret;
>
> /* Traverse the guest's 2nd-level tree, allocate new levels needed */
> - pgd = kvm->arch.pgtable + pgd_index(gpa);
> + pgd = pgtable + pgd_index(gpa);
> pud = NULL;
> if (pgd_present(*pgd))
> pud = pud_offset(pgd, gpa);
> @@ -565,95 +566,49 @@ static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
> return ret;
> }
>
> -int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> - unsigned long ea, unsigned long dsisr)
> +static bool kvmppc_hv_handle_set_rc(struct kvm *kvm, pgd_t *pgtable,
> + bool writing, unsigned long gpa)
> +{
> + unsigned long pgflags;
> + unsigned int shift;
> + pte_t *ptep;
> +
> + /*
> + * Need to set an R or C bit in the 2nd-level tables;
> + * since we are just helping out the hardware here,
> + * it is sufficient to do what the hardware does.
> + */
> + pgflags = _PAGE_ACCESSED;
> + if (writing)
> + pgflags |= _PAGE_DIRTY;
> + /*
> + * We are walking the secondary (partition-scoped) page table here.
> + * We can do this without disabling irq because the Linux MM
> + * subsystem doesn't do THP splits and collapses on this tree.
> + */
> + ptep = __find_linux_pte(pgtable, gpa, NULL, &shift);
> + if (ptep && pte_present(*ptep) && (!writing || pte_write(*ptep))) {
> + kvmppc_radix_update_pte(kvm, ptep, 0, pgflags, gpa, shift);
> + return true;
> + }
> + return false;
> +}
> +
> +static int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
> + unsigned long gpa,
> + struct kvm_memory_slot *memslot,
> + bool writing, bool kvm_ro,
> + pte_t *inserted_pte, unsigned int *levelp)
> {
> struct kvm *kvm = vcpu->kvm;
> - unsigned long mmu_seq;
> - unsigned long gpa, gfn, hva;
> - struct kvm_memory_slot *memslot;
> struct page *page = NULL;
> - long ret;
> - bool writing;
> + unsigned long mmu_seq;
> + unsigned long hva, gfn = gpa >> PAGE_SHIFT;
> bool upgrade_write = false;
> bool *upgrade_p = &upgrade_write;
> pte_t pte, *ptep;
> - unsigned long pgflags;
> unsigned int shift, level;
> -
> - /* Check for unusual errors */
> - if (dsisr & DSISR_UNSUPP_MMU) {
> - pr_err("KVM: Got unsupported MMU fault\n");
> - return -EFAULT;
> - }
> - if (dsisr & DSISR_BADACCESS) {
> - /* Reflect to the guest as DSI */
> - pr_err("KVM: Got radix HV page fault with DSISR=%lx\n", dsisr);
> - kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
> - return RESUME_GUEST;
> - }
> -
> - /* Translate the logical address and get the page */
> - gpa = vcpu->arch.fault_gpa & ~0xfffUL;
> - gpa &= ~0xF000000000000000ul;
> - gfn = gpa >> PAGE_SHIFT;
> - if (!(dsisr & DSISR_PRTABLE_FAULT))
> - gpa |= ea & 0xfff;
> - memslot = gfn_to_memslot(kvm, gfn);
> -
> - /* No memslot means it's an emulated MMIO region */
> - if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
> - if (dsisr & (DSISR_PRTABLE_FAULT | DSISR_BADACCESS |
> - DSISR_SET_RC)) {
> - /*
> - * Bad address in guest page table tree, or other
> - * unusual error - reflect it to the guest as DSI.
> - */
> - kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
> - return RESUME_GUEST;
> - }
> - return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
> - dsisr & DSISR_ISSTORE);
> - }
> -
> - writing = (dsisr & DSISR_ISSTORE) != 0;
> - if (memslot->flags & KVM_MEM_READONLY) {
> - if (writing) {
> - /* give the guest a DSI */
> - dsisr = DSISR_ISSTORE | DSISR_PROTFAULT;
> - kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
> - return RESUME_GUEST;
> - }
> - upgrade_p = NULL;
> - }
> -
> - if (dsisr & DSISR_SET_RC) {
> - /*
> - * Need to set an R or C bit in the 2nd-level tables;
> - * since we are just helping out the hardware here,
> - * it is sufficient to do what the hardware does.
> - */
> - pgflags = _PAGE_ACCESSED;
> - if (writing)
> - pgflags |= _PAGE_DIRTY;
> - /*
> - * We are walking the secondary page table here. We can do this
> - * without disabling irq.
> - */
> - spin_lock(&kvm->mmu_lock);
> - ptep = __find_linux_pte(kvm->arch.pgtable,
> - gpa, NULL, &shift);
> - if (ptep && pte_present(*ptep) &&
> - (!writing || pte_write(*ptep))) {
> - kvmppc_radix_update_pte(kvm, ptep, 0, pgflags,
> - gpa, shift);
> - dsisr &= ~DSISR_SET_RC;
> - }
> - spin_unlock(&kvm->mmu_lock);
> - if (!(dsisr & (DSISR_BAD_FAULT_64S | DSISR_NOHPTE |
> - DSISR_PROTFAULT | DSISR_SET_RC)))
> - return RESUME_GUEST;
> - }
> + int ret;
>
> /* used to check for invalidations in progress */
> mmu_seq = kvm->mmu_notifier_seq;
> @@ -666,7 +621,7 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> * is that the page is writable.
> */
> hva = gfn_to_hva_memslot(memslot, gfn);
> - if (upgrade_p && __get_user_pages_fast(hva, 1, 1, &page) == 1) {
> + if (!kvm_ro && __get_user_pages_fast(hva, 1, 1, &page) == 1) {
> upgrade_write = true;
> } else {
> unsigned long pfn;
> @@ -724,7 +679,12 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> }
>
> /* Allocate space in the tree and write the PTE */
> - ret = kvmppc_create_pte(kvm, pte, gpa, level, mmu_seq);
> + ret = kvmppc_create_pte(kvm, kvm->arch.pgtable, pte, gpa, level,
> + mmu_seq);
> + if (inserted_pte)
> + *inserted_pte = pte;
> + if (levelp)
> + *levelp = level;
>
> if (page) {
> if (!ret && (pte_val(pte) & _PAGE_WRITE))
> @@ -732,6 +692,82 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> put_page(page);
> }
>
> + return ret;
> +}
> +
> +int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned long ea, unsigned long dsisr)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + unsigned long gpa, gfn;
> + struct kvm_memory_slot *memslot;
> + long ret;
> + bool writing = !!(dsisr & DSISR_ISSTORE);
> + bool kvm_ro = false;
> +
> + /* Check for unusual errors */
> + if (dsisr & DSISR_UNSUPP_MMU) {
> + pr_err("KVM: Got unsupported MMU fault\n");
> + return -EFAULT;
> + }
> + if (dsisr & DSISR_BADACCESS) {
> + /* Reflect to the guest as DSI */
> + pr_err("KVM: Got radix HV page fault with DSISR=%lx\n", dsisr);
> + kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
> + return RESUME_GUEST;
> + }
> +
> + /* Translate the logical address */
> + gpa = vcpu->arch.fault_gpa & ~0xfffUL;
> + gpa &= ~0xF000000000000000ul;
> + gfn = gpa >> PAGE_SHIFT;
> + if (!(dsisr & DSISR_PRTABLE_FAULT))
> + gpa |= ea & 0xfff;
> +
> + /* Get the corresponding memslot */
> + memslot = gfn_to_memslot(kvm, gfn);
> +
> + /* No memslot means it's an emulated MMIO region */
> + if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
> + if (dsisr & (DSISR_PRTABLE_FAULT | DSISR_BADACCESS |
> + DSISR_SET_RC)) {
> + /*
> + * Bad address in guest page table tree, or other
> + * unusual error - reflect it to the guest as DSI.
> + */
> + kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
> + return RESUME_GUEST;
> + }
> + return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea, writing);
> + }
> +
> + if (memslot->flags & KVM_MEM_READONLY) {
> + if (writing) {
> + /* give the guest a DSI */
> + kvmppc_core_queue_data_storage(vcpu, ea, DSISR_ISSTORE |
> + DSISR_PROTFAULT);
> + return RESUME_GUEST;
> + }
> + kvm_ro = true;
> + }
> +
> + /* Failed to set the reference/change bits */
> + if (dsisr & DSISR_SET_RC) {
> + spin_lock(&kvm->mmu_lock);
> + if (kvmppc_hv_handle_set_rc(kvm, kvm->arch.pgtable,
> + writing, gpa))
> + dsisr &= ~DSISR_SET_RC;
> + spin_unlock(&kvm->mmu_lock);
> +
> + if (!(dsisr & (DSISR_BAD_FAULT_64S | DSISR_NOHPTE |
> + DSISR_PROTFAULT | DSISR_SET_RC)))
> + return RESUME_GUEST;
> + }
> +
> + /* Try to insert a pte */
> + ret = kvmppc_book3s_instantiate_page(vcpu, gpa, memslot, writing,
> + kvm_ro, NULL, NULL);
> +
> if (ret == 0 || ret == -EAGAIN)
> ret = RESUME_GUEST;
> return ret;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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