From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH 08/10] KVM: introduce readonly_bad_hva Date: Fri, 20 Jul 2012 11:01:28 +0800 Message-ID: <5008CA08.6040804@linux.vnet.ibm.com> References: <5005791B.8040807@linux.vnet.ibm.com> <50057A73.40005@linux.vnet.ibm.com> <5007DE72.6030300@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Avi Kivity Return-path: In-Reply-To: <5007DE72.6030300@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 07/19/2012 06:16 PM, Avi Kivity wrote: > On 07/17/2012 05:45 PM, Xiao Guangrong wrote: >> In the later patch, it indicates failure when we try to get a writable >> hva from the readonly slot >> >> Signed-off-by: Xiao Guangrong >> --- >> virt/kvm/kvm_main.c | 12 +++++++++++- >> 1 files changed, 11 insertions(+), 1 deletions(-) >> >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index b70f1a4..c056736 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -994,9 +994,19 @@ static inline unsigned long bad_hva(void) >> return PAGE_OFFSET; >> } >> >> +static inline unsigned long readonly_bad_hva(void) >> +{ >> + return PAGE_OFFSET + PAGE_SIZE; >> +} >> + >> +static int kvm_is_readonly_bad_hva(unsigned long addr) >> +{ >> + return addr == readonly_bad_hva(); >> +} >> + >> int kvm_is_error_hva(unsigned long addr) >> { >> - return addr == bad_hva(); >> + return addr == bad_hva() || kvm_is_readonly_bad_hva(addr); >> } > > addr >= PAGE_OFFSET. Or change it to use -E*. I prefer to the first one, addr >= PAGE_OFFSET, all virtual addresses between 0 and (~0ULL) are valid, Using PAGE_OFFSET is more readable. [ is_error_pfn is suitable to use -err because the the range of physical address is always limited, for example, 0 ~ 64G on x86.]