From mboxrd@z Thu Jan 1 00:00:00 1970 From: KarimAllah Ahmed Subject: [PATCH] kvm: Map PFN-type memory regions as writable (if possible) Date: Wed, 17 Jan 2018 18:26:05 +0100 Message-ID: <1516209965-18614-1-git-send-email-karahmed@amazon.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: KarimAllah Ahmed , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , linux-kernel@vger.kernel.org To: kvm@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 --- virt/kvm/kvm_main.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 97da45e..0efb089 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1534,6 +1534,8 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, goto retry; if (r < 0) pfn = KVM_PFN_ERR_FAULT; + if (writable) + *writable = true; } else { if (async && vma_is_valid(vma, write_fault)) *async = true; -- 2.7.4