From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Paul Mackerras <paulus@ozlabs.org>,
linux-mm@kvack.org, kvmarm@lists.cs.columbia.edu,
Dave Jiang <dave.jiang@intel.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Marc Zyngier <maz@kernel.org>, Joerg Roedel <joro@8bytes.org>,
syzbot+c9d1fb51ac9d0d10c39d@syzkaller.appspotmail.com,
Barret Rhoden <brho@google.com>,
kvm-ppc@vger.kernel.org, Liran Alon <liran.alon@oracle.com>,
Andy Lutomirski <luto@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org,
Jim Mattson <jmattson@google.com>,
linux-kernel@vger.kernel.org,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jason Zeng <jason.zeng@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: [PATCH 04/14] KVM: Play nice with read-only memslots when querying host page size
Date: Wed, 8 Jan 2020 12:24:38 -0800 [thread overview]
Message-ID: <20200108202448.9669-5-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200108202448.9669-1-sean.j.christopherson@intel.com>
Open code an equivalent of kvm_vcpu_gfn_to_memslot() when querying the
host page size to avoid the "writable" check in __gfn_to_hva_many(),
which will always fail on read-only memslots due to gfn_to_hva()
assuming writes. Functionally, this allows x86 to create large mappings
for read-only memslots that are backed by HugeTLB mappings.
Note, the changelog for commit 05da45583de9 ("KVM: MMU: large page
support") states "If the largepage contains write-protected pages, a
large pte is not used.", but "write-protected" refers to pages that are
temporarily read-only, e.g. read-only memslots didn't even exist at the
time.
Fixes: 4d8b81abc47b ("KVM: introduce readonly memslot")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
virt/kvm/kvm_main.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5f7f06824c2b..d9aced677ddd 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1418,15 +1418,23 @@ EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn)
{
+ struct kvm_memory_slot *slot;
struct vm_area_struct *vma;
unsigned long addr, size;
size = PAGE_SIZE;
- addr = kvm_vcpu_gfn_to_hva(vcpu, gfn);
- if (kvm_is_error_hva(addr))
+ /*
+ * Manually do the equivalent of kvm_vcpu_gfn_to_hva() to avoid the
+ * "writable" check in __gfn_to_hva_many(), which will always fail on
+ * read-only memslots due to gfn_to_hva() assuming writes.
+ */
+ slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+ if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
return PAGE_SIZE;
+ addr = __gfn_to_hva_memslot(slot, gfn);
+
down_read(¤t->mm->mmap_sem);
vma = find_vma(current->mm, addr);
if (!vma)
--
2.24.1
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next prev parent reply other threads:[~2020-01-08 20:27 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-08 20:24 [PATCH 00/14] KVM: x86/mmu: Huge page fixes, cleanup, and DAX Sean Christopherson
2020-01-08 20:24 ` [PATCH 01/14] KVM: x86/mmu: Enforce max_level on HugeTLB mappings Sean Christopherson
2020-01-08 20:24 ` [PATCH 02/14] mm: thp: KVM: Explicitly check for THP when populating secondary MMU Sean Christopherson
2020-01-08 20:24 ` [PATCH 03/14] KVM: Use vcpu-specific gva->hva translation when querying host page size Sean Christopherson
2020-01-08 20:24 ` Sean Christopherson [this message]
2020-01-21 14:24 ` [PATCH 04/14] KVM: Play nice with read-only memslots " Paolo Bonzini
2020-01-08 20:24 ` [PATCH 05/14] x86/mm: Introduce lookup_address_in_mm() Sean Christopherson
2020-01-09 21:04 ` Thomas Gleixner
2020-01-21 14:26 ` Paolo Bonzini
2020-01-08 20:24 ` [PATCH 06/14] KVM: x86/mmu: Refactor THP adjust to prep for changing query Sean Christopherson
2020-01-08 20:24 ` [PATCH 07/14] KVM: x86/mmu: Walk host page tables to find THP mappings Sean Christopherson
2020-01-21 14:40 ` Paolo Bonzini
2020-01-08 20:24 ` [PATCH 08/14] KVM: x86/mmu: Drop level optimization from fast_page_fault() Sean Christopherson
2020-01-08 20:24 ` [PATCH 09/14] KVM: x86/mmu: Rely on host page tables to find HugeTLB mappings Sean Christopherson
2020-01-08 20:24 ` [PATCH 10/14] KVM: x86/mmu: Remove obsolete gfn restoration in FNAME(fetch) Sean Christopherson
2020-01-08 20:24 ` [PATCH 11/14] KVM: x86/mmu: Zap any compound page when collapsing sptes Sean Christopherson
2020-01-08 20:24 ` [PATCH 12/14] KVM: x86/mmu: Fold max_mapping_level() into kvm_mmu_hugepage_adjust() Sean Christopherson
2020-01-21 15:12 ` Paolo Bonzini
2020-01-08 20:24 ` [PATCH 13/14] KVM: x86/mmu: Remove lpage_is_disallowed() check from set_spte() Sean Christopherson
2020-01-08 20:24 ` [PATCH 14/14] KVM: x86/mmu: Use huge pages for DAX-backed files Sean Christopherson
2020-01-09 19:47 ` [PATCH 00/14] KVM: x86/mmu: Huge page fixes, cleanup, and DAX Barret Rhoden
2020-01-21 15:10 ` Paolo Bonzini
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