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KVM: PPC: Book3S HV: Refactor radix page fault handler
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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@ozlabs.org - reduced diffs from previous code]

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Suraj Jitindar Singh authored and Michael Ellerman committed Oct 9, 2018
1 parent 9811c78 commit 04bae9d
Showing 1 changed file with 123 additions and 87 deletions.
210 changes: 123 additions & 87 deletions arch/powerpc/kvm/book3s_64_mmu_radix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -724,14 +679,95 @@ 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))
set_page_dirty_lock(page);
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;
Expand Down

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