2016-10-26 23:40+0200, Laszlo Ersek: > On 10/26/16 22:50, Radim Krčmář wrote: >> [1/2] adds the emulation (and could be split into two patches if you'd like), >> [2/2] just refactors the code. >> >> This should fix an issue that users are hitting. Laszlo found several >> reports: >> - https://bugs.launchpad.net/qemu/+bug/1623276 >> - https://bugzilla.proxmox.com/show_bug.cgi?id=1182 >> - https://bugs.archlinux.org/task/50778 >> >> I have only tested it with a simple kvm-unit-tests, though. Reproducing the >> iPXE issue is on the way ... >> >> >> Radim Krčmář (2): >> KVM: x86: emulate fxsave and fxrstor >> KVM: x86: save one bit in ctxt->d >> >> arch/x86/kvm/emulate.c | 110 >> ++++++++++++++++++++++++++++++++++++++++++------- >> 1 file changed, 94 insertions(+), 16 deletions(-) >> > > I was just about to post iPXE patches that would disable the FXSAVE / > FXRSTOR instructions in the CONFIG=qemu build (*), but you beat me to it > with the KVM emulation code ;) > > (*) If you look at the iPXE commit that added them, they are a > workaround for a Tivoli VMM bug; i.e., irrelevant for QEMU/KVM guests. > > ... Actually, those iPXE patches that conditionalize FXSAVE / FXRSTOR > may still make sense -- we can rebuild iPXE, and bundle the refreshed > binaries with QEMU v2.7.1, and swiftly at that. Whereas the KVM patches > could take more time to propagate to users?... Not sure. What do you > guys think?
This series won't get into 4.9, so it would take almost half a year before the kernel trickles into experimental distros. And updating QEMU/iPXE isn't as dangerous as updating kernel, so I like the idea. I am just tempted to drop a KVM patch with positive diffstat that fixes something that doesn't really need fixing anymore. :)
