Messages in this thread | | | Date | Fri, 10 Aug 2012 15:14:22 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH v5 00/12] KVM: introduce readonly memslot |
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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?
The initial objective was to fix a vm crash, can you explain that initial problem?
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