From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: [PATCH 06/10] KVM: use 'writable' as a hint to map writable pfn Date: Tue, 17 Jul 2012 22:43:47 +0800 Message-ID: <50057A23.6080704@linux.vnet.ibm.com> References: <5005791B.8040807@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Marcelo Tosatti , LKML , KVM To: Xiao Guangrong Return-path: Received: from e28smtp03.in.ibm.com ([122.248.162.3]:43500 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752258Ab2GQOn6 (ORCPT ); Tue, 17 Jul 2012 10:43:58 -0400 Received: from /spool/local by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 17 Jul 2012 20:13:55 +0530 In-Reply-To: <5005791B.8040807@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: In current code, we always map writable pfn for the read-fault, in order to support readonly memslot, we map writable pfn only if 'writable' is not NULL Signed-off-by: Xiao Guangrong --- virt/kvm/kvm_main.c | 24 +++++++++++++++++++++++- 1 files changed, 23 insertions(+), 1 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 54fb47b..e9eab07 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1109,6 +1109,14 @@ static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async, if (!(async || atomic)) return false; + /* + * Fast pin a writable pfn only if it is a write fault request + * or the caller allows to map a writable pfn for a read fault + * request. + */ + if (!(write_fault || writable)) + return false; + npages = __get_user_pages_fast(addr, 1, 1, page); if (npages == 1) { *pfn = page_to_pfn(page[0]); @@ -1149,7 +1157,7 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, return npages; /* map read fault as writable if possible */ - if (unlikely(!write_fault)) { + if (unlikely(!write_fault) && writable) { struct page *wpage[1]; npages = __get_user_pages_fast(addr, 1, 1, wpage); @@ -1165,6 +1173,20 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, return npages; } +/* + * Pin guest page in memory and return its pfn. + * @addr: host virtual address which maps memory to the guest + * @atomic: whether this function can sleep + * @async: whether this function need to wait IO complete if the + * host page is not in the memory + * @write_fault: whether we should get a writable host page + * @writable: whether it allows to map a writable host page for !@write_fault + * + * The function will map a writable host page for these two cases: + * 1): @write_fault = true + * 2): @write_fault = false && @writable, @writable will tell the caller + * whether the mapping is writable. + */ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, bool write_fault, bool *writable) { -- 1.7.7.6