From d757c3a9cf4a8af26d085054731ebd9b5bc9983c Mon Sep 17 00:00:00 2001 From: KarimAllah Ahmed Date: Wed, 17 Jan 2018 19:18:56 +0100 Subject: [PATCH] kvm: Map PFN-type memory regions as writable (if possible) MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit a340b3e229b24a56f1c7f5826b15a3af0f4b13e5 ] For EPT-violations that are triggered by a read, the pages are also mapped with write permissions (if their memory region is also writable). That would avoid getting yet another fault on the same page when a write occurs. This optimization only happens when you have a "struct page" backing the memory region. So also enable it for memory regions that do not have a "struct page". Cc: Paolo Bonzini Cc: Radim Krčmář Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: KarimAllah Ahmed Reviewed-by: Paolo Bonzini Signed-off-by: Radim Krčmář Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- virt/kvm/kvm_main.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d81af263f50b..4f35f0dfe681 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1434,7 +1434,8 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) static int hva_to_pfn_remapped(struct vm_area_struct *vma, unsigned long addr, bool *async, - bool write_fault, kvm_pfn_t *p_pfn) + bool write_fault, bool *writable, + kvm_pfn_t *p_pfn) { unsigned long pfn; int r; @@ -1460,6 +1461,8 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, } + if (writable) + *writable = true; /* * Get a reference here because callers of *hva_to_pfn* and @@ -1525,7 +1528,7 @@ retry: if (vma == NULL) pfn = KVM_PFN_ERR_FAULT; else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) { - r = hva_to_pfn_remapped(vma, addr, async, write_fault, &pfn); + r = hva_to_pfn_remapped(vma, addr, async, write_fault, writable, &pfn); if (r == -EAGAIN) goto retry; if (r < 0) -- 2.20.1