From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Anthony Liguori <anthony@codemonkey.ws>,
"Kevin O'Connor" <kevin@koconnor.net>,
Liu Sheng <liusheng@linux.vnet.ibm.com>,
KVM <kvm@vger.kernel.org>,
qemu-devel@nongnu.org
Subject: Re: [PATCH v2 3/5] Qemu: do not mark bios readonly
Date: Wed, 31 Oct 2012 15:01:27 +0800 [thread overview]
Message-ID: <5090CCC7.9060503@linux.vnet.ibm.com> (raw)
In-Reply-To: <5090C94C.8080808@web.de>
On 10/31/2012 02:46 PM, Jan Kiszka wrote:
>> Please allow me to clarify it more clearly.
>>
>> The flash is ROMD device means guest can not write it, any kinds of guest write
>> access on this device can cause vmexit to kvm and return to userspace.
>>
>> We should pay more attention on it if we execute the code in ROMD since we
>> can not use ROMD as stack/page table/IDT table and all other implicitly write access.
>> Of course, if you do not use ROM as those purposes, it is okay. :)
>
> So the problem is that there is KVM code that still blindly writes to
> guest memory and does not take the memory regions' protection flag into
> account? And we cannot mark those regions read only in the host's page
> table?
KVM has the ability to catch this kind of write access on ROMD, it is just hard to
emulate the implicitly memory access.
next prev parent reply other threads:[~2012-10-31 7:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 9:20 [PATCH v2 0/5] Qemu: implement readonly memory Xiao Guangrong
2012-10-25 9:21 ` [PATCH v2 1/5] KVM: define KVM_CAP_READONLY_MEM unconditionally Xiao Guangrong
2012-10-25 12:14 ` Jan Kiszka
2012-10-25 9:21 ` [PATCH v2 2/5] Qemu: update header files Xiao Guangrong
2012-10-25 11:03 ` [Qemu-devel] " Peter Maydell
2012-10-25 9:22 ` [PATCH v2 3/5] Qemu: do not mark bios readonly Xiao Guangrong
2012-10-26 10:35 ` Jan Kiszka
2012-10-29 7:09 ` Xiao Guangrong
2012-10-29 7:44 ` Jan Kiszka
2012-10-29 8:31 ` Xiao Guangrong
2012-10-31 6:03 ` Jan Kiszka
2012-10-31 6:35 ` Xiao Guangrong
2012-10-31 6:46 ` Jan Kiszka
2012-10-31 7:01 ` Xiao Guangrong [this message]
2012-10-31 7:21 ` Jan Kiszka
2012-10-25 9:22 ` [PATCH v2 4/5] Qemu: implement readonly memory Xiao Guangrong
2012-10-25 9:23 ` [PATCH v2 5/5] Qemu: mark pci rom readonly Xiao Guangrong
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