On 06/17/16 13:21, Raj, Ashok wrote: > On Fri, Jun 17, 2016 at 07:31:08PM +0200, Laszlo Ersek wrote: > > >> > > >> On 16/06/2016 08:06, Haozhong Zhang wrote: > > >>> It's a prerequisite that certain bits of MSR_IA32_FEATURE_CONTROL should > > >>> be set before some features (e.g. VMX and LMCE) can be used, which is > > >>> usually done by the firmware. This patch adds a fw_cfg file > > >>> "etc/msr_feature_control" which contains the advised value of > > >>> MSR_IA32_FEATURE_CONTROL and can be used by guest firmware (e.g. SeaBIOS). > > >>> > > I'm sorry i'm joining this discussion a bit late returning from vacation. > In a real platform supporting LMCE, BIOS is responsible for setting the bits > for IA32_FEATURE_CONTROL correctly. There are good reasons why we want the > BIOS to play this role. > > in a virtualized environment, do we really have to push the same requirement > or would it suffice to just emulate it as we did in the early patches. > > Not sure what exact problem is created by just simply supporting it within > kvm/qemu and not needing the bios for the guest to also adapt these changes. > In the current nested VMX implementation in QEMU, setup MSR_IA32_FEATURE_CONTROL is left to guest. So I think, for LMCE which is another feature involving MSR_IA32_FEATURE_CONTROL, we may follow the existing code. Paolo and Radim, is there any case that objects to setting MSR_IA32_FEATURE_CONTROL in QEMU? Thanks, Haozhong -- 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
