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KVM: PPC: Book3S HV: Handle 1GB pages in radix page fault handler
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This adds code to the radix hypervisor page fault handler to handle the
case where the guest memory is backed by 1GB hugepages, and put them
into the partition-scoped radix tree at the PUD level.  The code is
essentially analogous to the code for 2MB pages.  This also rearranges
kvmppc_create_pte() to make it easier to follow.

Signed-off-by: Paul Mackerras <[email protected]>
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@paulusmack
paulusmack committed Mar 18, 2018
1 parent f7caf71 commit 58c5c27
Showing 1 changed file with 93 additions and 36 deletions.
129 changes: 93 additions & 36 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 @@ -150,7 +150,9 @@ static void kvmppc_radix_tlbie_page(struct kvm *kvm, unsigned long addr,
{
int psize = MMU_BASE_PSIZE;

if (pshift >= PMD_SHIFT)
if (pshift >= PUD_SHIFT)
psize = MMU_PAGE_1G;
else if (pshift >= PMD_SHIFT)
psize = MMU_PAGE_2M;
addr &= ~0xfffUL;
addr |= mmu_psize_defs[psize].ap << 5;
Expand Down Expand Up @@ -231,9 +233,9 @@ static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
new_pud = pud_alloc_one(kvm->mm, gpa);

pmd = NULL;
if (pud && pud_present(*pud))
if (pud && pud_present(*pud) && !pud_huge(*pud))
pmd = pmd_offset(pud, gpa);
else
else if (level <= 1)
new_pmd = pmd_alloc_one(kvm->mm, gpa);

if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_is_leaf(*pmd)))
Expand All @@ -254,6 +256,50 @@ static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
new_pud = NULL;
}
pud = pud_offset(pgd, gpa);
if (pud_huge(*pud)) {
unsigned long hgpa = gpa & PUD_MASK;

/*
* If we raced with another CPU which has just put
* a 1GB pte in after we saw a pmd page, try again.
*/
if (level <= 1 && !new_pmd) {
ret = -EAGAIN;
goto out_unlock;
}
/* Check if we raced and someone else has set the same thing */
if (level == 2 && pud_raw(*pud) == pte_raw(pte)) {
ret = 0;
goto out_unlock;
}
/* Valid 1GB page here already, remove it */
old = kvmppc_radix_update_pte(kvm, (pte_t *)pud,
~0UL, 0, hgpa, PUD_SHIFT);
kvmppc_radix_tlbie_page(kvm, hgpa, PUD_SHIFT);
if (old & _PAGE_DIRTY) {
unsigned long gfn = hgpa >> PAGE_SHIFT;
struct kvm_memory_slot *memslot;
memslot = gfn_to_memslot(kvm, gfn);
if (memslot && memslot->dirty_bitmap)
kvmppc_update_dirty_map(memslot,
gfn, PUD_SIZE);
}
}
if (level == 2) {
if (!pud_none(*pud)) {
/*
* There's a page table page here, but we wanted to
* install a large page, so remove and free the page
* table page. new_pmd will be NULL since level == 2.
*/
new_pmd = pmd_offset(pud, 0);
pud_clear(pud);
kvmppc_radix_flush_pwc(kvm, gpa);
}
kvmppc_radix_set_pte_at(kvm, gpa, (pte_t *)pud, pte);
ret = 0;
goto out_unlock;
}
if (pud_none(*pud)) {
if (!new_pmd)
goto out_unlock;
Expand Down Expand Up @@ -289,41 +335,43 @@ static int kvmppc_create_pte(struct kvm *kvm, pte_t pte, unsigned long gpa,
kvmppc_update_dirty_map(memslot,
gfn, PMD_SIZE);
}
} else if (level == 1 && !pmd_none(*pmd)) {
/*
* There's a page table page here, but we wanted to
* install a large page, so remove and free the page
* table page. new_ptep will be NULL since level == 1.
*/
new_ptep = pte_offset_kernel(pmd, 0);
pmd_clear(pmd);
kvmppc_radix_flush_pwc(kvm, gpa);
}
if (level == 0) {
if (pmd_none(*pmd)) {
if (!new_ptep)
goto out_unlock;
pmd_populate(kvm->mm, pmd, new_ptep);
new_ptep = NULL;
}
ptep = pte_offset_kernel(pmd, gpa);
if (pte_present(*ptep)) {
/* Check if someone else set the same thing */
if (pte_raw(*ptep) == pte_raw(pte)) {
ret = 0;
goto out_unlock;
}
/* PTE was previously valid, so invalidate it */
old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_PRESENT,
0, gpa, 0);
kvmppc_radix_tlbie_page(kvm, gpa, 0);
if (old & _PAGE_DIRTY)
mark_page_dirty(kvm, gpa >> PAGE_SHIFT);
if (level == 1) {
if (!pmd_none(*pmd)) {
/*
* There's a page table page here, but we wanted to
* install a large page, so remove and free the page
* table page. new_ptep will be NULL since level == 1.
*/
new_ptep = pte_offset_kernel(pmd, 0);
pmd_clear(pmd);
kvmppc_radix_flush_pwc(kvm, gpa);
}
kvmppc_radix_set_pte_at(kvm, gpa, ptep, pte);
} else {
kvmppc_radix_set_pte_at(kvm, gpa, pmdp_ptep(pmd), pte);
ret = 0;
goto out_unlock;
}
if (pmd_none(*pmd)) {
if (!new_ptep)
goto out_unlock;
pmd_populate(kvm->mm, pmd, new_ptep);
new_ptep = NULL;
}
ptep = pte_offset_kernel(pmd, gpa);
if (pte_present(*ptep)) {
/* Check if someone else set the same thing */
if (pte_raw(*ptep) == pte_raw(pte)) {
ret = 0;
goto out_unlock;
}
/* PTE was previously valid, so invalidate it */
old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_PRESENT,
0, gpa, 0);
kvmppc_radix_tlbie_page(kvm, gpa, 0);
if (old & _PAGE_DIRTY)
mark_page_dirty(kvm, gpa >> PAGE_SHIFT);
}
kvmppc_radix_set_pte_at(kvm, gpa, ptep, pte);
ret = 0;

out_unlock:
Expand Down Expand Up @@ -446,8 +494,13 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
pfn = page_to_pfn(page);
if (PageCompound(page)) {
pte_size <<= compound_order(compound_head(page));
/* See if we can insert a 2MB large-page PTE here */
if (pte_size >= PMD_SIZE &&
/* See if we can insert a 1GB or 2MB large PTE here */
if (pte_size >= PUD_SIZE &&
(gpa & (PUD_SIZE - PAGE_SIZE)) ==
(hva & (PUD_SIZE - PAGE_SIZE))) {
level = 2;
pfn &= ~((PUD_SIZE >> PAGE_SHIFT) - 1);
} else if (pte_size >= PMD_SIZE &&
(gpa & (PMD_SIZE - PAGE_SIZE)) ==
(hva & (PMD_SIZE - PAGE_SIZE))) {
level = 1;
Expand Down Expand Up @@ -657,6 +710,10 @@ void kvmppc_free_radix(struct kvm *kvm)
for (iu = 0; iu < PTRS_PER_PUD; ++iu, ++pud) {
if (!pud_present(*pud))
continue;
if (pud_huge(*pud)) {
pud_clear(pud);
continue;
}
pmd = pmd_offset(pud, 0);
for (im = 0; im < PTRS_PER_PMD; ++im, ++pmd) {
if (pmd_is_leaf(*pmd)) {
Expand Down

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