The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 42cde48b2d39772dba47e680781a32a6c4b7dc33 Mon Sep 17 00:00:00 2001

From: Sean Christopherson sean.j.christopherson@intel.com Date: Wed, 8 Jan 2020 12:24:38 -0800 Subject: [PATCH] KVM: Play nice with read-only memslots when querying host page size

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

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f6f8ffc2e865..eb3709d55139 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1409,7 +1409,7 @@ 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;