From: Marcelo Tosatti <mtosatti@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v5 00/12] KVM: introduce readonly memslot
Date: Tue, 14 Aug 2012 12:51:06 -0300 [thread overview]
Message-ID: <20120814155106.GA22249@amt.cnet> (raw)
In-Reply-To: <502A5A01.6040505@redhat.com>
On Tue, Aug 14, 2012 at 05:00:33PM +0300, Avi Kivity wrote:
> On 08/10/2012 09:14 PM, Marcelo Tosatti wrote:
> > On Tue, Aug 07, 2012 at 05:47:15PM +0800, Xiao Guangrong wrote:
> >> Changelog:
> >> - introduce KVM_PFN_ERR_RO_FAULT instead of dummy page
> >> - introduce KVM_HVA_ERR_BAD and optimize error hva indicators
> >>
> >> The test case can be found at:
> >> http://lkml.indiana.edu/hypermail/linux/kernel/1207.2/00819/migrate-perf.tar.bz2
> >>
> >> In current code, if we map a readonly memory space from host to guest
> >> and the page is not currently mapped in the host, we will get a fault-pfn
> >> and async is not allowed, then the vm will crash.
> >>
> >> As Avi's suggestion, We introduce readonly memory region to map ROM/ROMD
> >> to the guest, read access is happy for readonly memslot, write access on
> >> readonly memslot will cause KVM_EXIT_MMIO exit.
> >
> > Memory slots whose QEMU mapping is write protected is supported
> > today, as long as there are no write faults.
> >
> > What prevents the use of mmap(!MAP_WRITE) to handle read-only memslots
> > again?
>
> Userspace may want to modify the ROM (for example, when programming a
> flash device). It is also possible to map an hva range rw through one
> slot and ro through another.
Right, can do that with multiple userspace maps to the same anonymous
memory region (see other email).
The bugs noticed should be fixed.
next prev parent reply other threads:[~2012-08-14 15:51 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-07 9:47 [PATCH v5 00/12] KVM: introduce readonly memslot Xiao Guangrong
2012-08-07 9:48 ` [PATCH v5 01/12] KVM: fix missing check for memslot flags Xiao Guangrong
2012-08-07 9:48 ` [PATCH v5 02/12] KVM: hide KVM_MEMSLOT_INVALID from userspace Xiao Guangrong
2012-08-09 18:48 ` Marcelo Tosatti
2012-08-10 2:11 ` Xiao Guangrong
2012-08-07 9:49 ` [PATCH v5 03/12] KVM: introduce gfn_to_pfn_memslot_atomic Xiao Guangrong
2012-08-09 18:50 ` Marcelo Tosatti
2012-08-10 3:22 ` Xiao Guangrong
2012-08-07 9:50 ` [PATCH v5 04/12] KVM: introduce gfn_to_hva_read/kvm_read_hva/kvm_read_hva_atomic Xiao Guangrong
2012-08-07 9:51 ` [PATCH v5 05/12] KVM: reorganize hva_to_pfn Xiao Guangrong
2012-08-10 17:51 ` Marcelo Tosatti
2012-08-11 3:11 ` Xiao Guangrong
2012-08-07 9:51 ` [PATCH v5 06/12] KVM: use 'writable' as a hint to map writable pfn Xiao Guangrong
2012-08-07 9:52 ` [PATCH v5 07/12] KVM: introduce KVM_PFN_ERR_RO_FAULT Xiao Guangrong
2012-08-07 9:52 ` [PATCH v5 08/12] KVM: introduce KVM_HVA_ERR_BAD Xiao Guangrong
2012-08-07 9:53 ` [PATCH v5 09/12] KVM: introduce KVM_HVA_ERR_RO_BAD Xiao Guangrong
2012-08-07 9:54 ` [PATCH v5 10/12] KVM: introduce readonly memslot Xiao Guangrong
2012-08-07 9:54 ` [PATCH v5 11/12] KVM: x86: introduce set_mmio_exit_info Xiao Guangrong
2012-08-10 18:03 ` Marcelo Tosatti
2012-08-11 3:13 ` Xiao Guangrong
2012-08-07 9:55 ` [PATCH v5 12/12] KVM: indicate readonly access fault Xiao Guangrong
2012-08-10 18:14 ` [PATCH v5 00/12] KVM: introduce readonly memslot Marcelo Tosatti
2012-08-11 3:36 ` Xiao Guangrong
2012-08-13 17:39 ` Marcelo Tosatti
2012-08-14 2:58 ` Xiao Guangrong
2012-08-14 15:25 ` Marcelo Tosatti
2012-08-16 5:49 ` Xiao Guangrong
2012-08-16 16:03 ` Marcelo Tosatti
2012-08-14 14:00 ` Avi Kivity
2012-08-14 15:51 ` Marcelo Tosatti [this message]
2012-08-15 10:44 ` Avi Kivity
2012-08-15 17:53 ` Marcelo Tosatti
2012-08-16 9:03 ` Avi Kivity
2012-08-16 15:57 ` Marcelo Tosatti
2012-08-16 16:17 ` Avi Kivity
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