From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58326) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWlKp-0004u8-9J for qemu-devel@nongnu.org; Mon, 29 Apr 2013 06:29:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UWlKo-0004Fm-DB for qemu-devel@nongnu.org; Mon, 29 Apr 2013 06:29:27 -0400 Received: from david.siemens.de ([192.35.17.14]:21359) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UWlKo-0004Fc-3g for qemu-devel@nongnu.org; Mon, 29 Apr 2013 06:29:26 -0400 Message-ID: <517E4B7F.6080709@siemens.com> Date: Mon, 29 Apr 2013 12:29:19 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <1367137941-4310-1-git-send-email-jordan.l.justen@intel.com> <1367137941-4310-4-git-send-email-jordan.l.justen@intel.com> In-Reply-To: <1367137941-4310-4-git-send-email-jordan.l.justen@intel.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/6] kvm: workaround a possible KVM bug when using KVM_MEM_READONLY List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jordan Justen Cc: qemu-devel@nongnu.org, Xiao Guangrong On 2013-04-28 10:32, Jordan Justen wrote: > On a Linux 3.8.0 based kernel, I occasionally saw a situation > where the memory region would continue to trap on memory > read even though KVM_MEM_READONLY was set. Only 3.8.0? Did you bisect the issue down to the causing commit? Is it fixed in later versions? Jan > > I found that if I set the slot to a size of 0, and before > setting the slot, it would then behave as expected. > > Signed-off-by: Jordan Justen > Cc: Xiao Guangrong > --- > kvm-all.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kvm-all.c b/kvm-all.c > index 95e6bf2..e2ddbcb 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -205,6 +205,13 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot) > if (s->migration_log) { > mem.flags |= KVM_MEM_LOG_DIRTY_PAGES; > } > + if (mem.flags & KVM_MEM_READONLY && mem.memory_size != 0) { > + /* Workaround an issue with setting a READONLY slot. Set the > + * slot size to 0 before setting the slot to the desired value. */ > + mem.memory_size = 0; > + kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem); > + mem.memory_size = slot->memory_size; > + } > return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem); > } > > -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux