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KVM: Play nice with read-only memslots when querying host page size

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[ Upstream commit 42cde48b2d39772dba47e680781a32a6c4b7dc33 ]

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>
[Redone using kvm_vcpu_gfn_to_memslot_prot. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sean Christopherson 2020-01-08 12:24:38 -08:00 committed by Greg Kroah-Hartman
parent f8d4d63d8c
commit 0941ce401d
1 changed files with 1 additions and 1 deletions
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2
virt/kvm/kvm_main.c
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@ -1284,7 +1284,7 @@ unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn)
size = PAGE_SIZE;
addr = kvm_vcpu_gfn_to_hva(vcpu, gfn);
addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gfn, NULL);
if (kvm_is_error_hva(addr))
return PAGE_SIZE;