path: root/arch/powerpc/kvm/book3s_hv_rm_mmu.c
diff options
authorPaul Mackerras <paulus@samba.org>2013-11-16 17:46:02 +1100
committerAlexander Graf <agraf@suse.de>2013-11-18 22:36:09 +0100
commitcaaa4c804fae7bb654f7d00b35b8583280a9c52c (patch)
tree1017d018bedf69d6e3dab27660fcc8ad4ac82f12 /arch/powerpc/kvm/book3s_hv_rm_mmu.c
parentf080480488028bcc25357f85e8ae54ccc3bb7173 (diff)
KVM: PPC: Book3S HV: Fix physical address calculations
This fixes a bug in kvmppc_do_h_enter() where the physical address for a page can be calculated incorrectly if transparent huge pages (THP) are active. Until THP came along, it was true that if we encountered a large (16M) page in kvmppc_do_h_enter(), then the associated memslot must be 16M aligned for both its guest physical address and the userspace address, and the physical address calculations in kvmppc_do_h_enter() assumed that. With THP, that is no longer true. In the case where we are using MMU notifiers and the page size that we get from the Linux page tables is larger than the page being mapped by the guest, we need to fill in some low-order bits of the physical address. Without THP, these bits would be the same in the guest physical address (gpa) and the host virtual address (hva). With THP, they can be different, and we need to use the bits from hva rather than gpa. In the case where we are not using MMU notifiers, the host physical address we get from the memslot->arch.slot_phys[] array already includes the low-order bits down to the PAGE_SIZE level, even if we are using large pages. Thus we can simplify the calculation in this case to just add in the remaining bits in the case where PAGE_SIZE is 64k and the guest is mapping a 4k page. The same bug exists in kvmppc_book3s_hv_page_fault(). The basic fix is to use psize (the page size from the HPTE) rather than pte_size (the page size from the Linux PTE) when updating the HPTE low word in r. That means that pfn needs to be computed to PAGE_SIZE granularity even if the Linux PTE is a huge page PTE. That can be arranged simply by doing the page_to_pfn() before setting page to the head of the compound page. If psize is less than PAGE_SIZE, then we need to make sure we only update the bits from PAGE_SIZE upwards, in order not to lose any sub-page offset bits in r. On the other hand, if psize is greater than PAGE_SIZE, we need to make sure we don't bring in non-zero low order bits in pfn, hence we mask (pfn << PAGE_SHIFT) with ~(psize - 1). Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/kvm/book3s_hv_rm_mmu.c')
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 9c515440ad1a..fddbf989f37e 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -225,6 +225,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
is_io = pa & (HPTE_R_I | HPTE_R_W);
pte_size = PAGE_SIZE << (pa & KVMPPC_PAGE_ORDER_MASK);
pa &= PAGE_MASK;
+ pa |= gpa & ~PAGE_MASK;
} else {
/* Translate to host virtual address */
hva = __gfn_to_hva_memslot(memslot, gfn);
@@ -238,13 +239,12 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
ptel = hpte_make_readonly(ptel);
is_io = hpte_cache_bits(pte_val(pte));
pa = pte_pfn(pte) << PAGE_SHIFT;
+ pa |= hva & (pte_size - 1);
if (pte_size < psize)
- if (pa && pte_size > psize)
- pa |= gpa & (pte_size - 1);
ptel &= ~(HPTE_R_PP0 - psize);
ptel |= pa;

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