From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:40137) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UXR2f-0002wA-Td for qemu-devel@nongnu.org; Wed, 01 May 2013 03:01:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UXR2b-0003ic-Gd for qemu-devel@nongnu.org; Wed, 01 May 2013 03:01:29 -0400 Received: from mga14.intel.com ([143.182.124.37]:41874) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UXR2b-0003iD-9m for qemu-devel@nongnu.org; Wed, 01 May 2013 03:01:25 -0400 From: Jordan Justen Date: Tue, 30 Apr 2013 23:56:30 -0700 Message-Id: <1367391393-6830-4-git-send-email-jordan.l.justen@intel.com> In-Reply-To: <1367391393-6830-1-git-send-email-jordan.l.justen@intel.com> References: <1367391393-6830-1-git-send-email-jordan.l.justen@intel.com> Subject: [Qemu-devel] [PATCH v2 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: qemu-devel@nongnu.org Cc: Jordan Justen , Xiao Guangrong 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. 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); } -- 1.7.10.4