On Thu, 2013-01-17 at 19:20 +0200, Gleb Natapov wrote: > On Thu, Jan 17, 2013 at 10:12:06AM -0700, Alex Williamson wrote: > > On Thu, 2013-01-17 at 09:29 +0200, Gleb Natapov wrote: > > > On Thu, Jan 17, 2013 at 11:20:43AM +0800, Xiao Guangrong wrote: > > > > On 01/17/2013 03:07 AM, Marcelo Tosatti wrote: > > > > > On Fri, Jan 11, 2013 at 06:25:18PM +0900, Takuya Yoshikawa wrote: > > > > >> Patches 1 to 3 are trivial. > > > > >> > > > > >> Patch 4 is the main cause of the increased lines, but I think the new > > > > >> code makes it easier to understand why each condition in > > > > >> __kvm_set_memory_region() is there. > > > > >> > > > > >> If you don't agree with patch 4, please consider taking the rest of the > > > > >> series at this time. > > > > >> > > > > >> Takuya Yoshikawa (4): > > > > >> KVM: set_memory_region: Don't jump to out_free unnecessarily > > > > >> KVM: set_memory_region: Don't check for overlaps unless we create or move a slot > > > > >> KVM: set_memory_region: Remove unnecessary variable memslot > > > > >> KVM: set_memory_region: Identify the requested change explicitly > > > > >> > > > > >> virt/kvm/kvm_main.c | 94 ++++++++++++++++++++++++++++++++------------------- > > > > >> 1 files changed, 59 insertions(+), 35 deletions(-) > > > > >> > > > > >> -- > > > > >> 1.7.5.4 > > > > > > > > > > Reviewed-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > > > > > > > > > BTW, while at it, its probably worthwhile to restrict flags > > > > > modifications: change from flags = 0 to flags = read-only is > > > > > incomplete. Xiao, should it be allowed only during creation? > > > > > > > > Will Readonly memory be used for VM-mem-sharing in the future? > > > > I remember you mentioned about mem-sharing things before. ;) > > > > > > > > Actually, It is safe on KVM MMU because all the gfns in the slot > > > > can become readonly after calling __kvm_set_memory_region. It is > > > > unsafe on IOMMU, what need to be fixed is unmapping gfns on IOMMU > > > > when the flag is changed. > > > > > > Which means if we allow changing flags from 0 to read_only or back we > > > need to call kvm_iommu_map_pages() when flags change. BTW as far as I > > > see currently IOMMU maps everything as read/write not matter what flags > > > say. Looks like a bug. Alex? > > > > That's correct, legacy device assignment is always r/w. vfio handles > > this correctly. Thanks, > > > Does this mean that device can write into read only memory? For legacy assignment, I would expect yes. On bare metal, DMA from an I/O device can obviously circumvent processor based memory attributes, but here that might also include things like ROMs too. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
