On 25.07.2023 23:36, Andrew Cooper wrote: > With xl/libxl now able to control the policy bits for MSR_ARCH_CAPS, it is > safe to advertise to guests by default. In turn, we don't need the special > case to expose details to dom0. > > This advertises MSR_ARCH_CAPS to guests on *all* Intel hardware, even if the > register content ends up being empty. This is necessary in order to safely > level two hosts which cross the Broadwell/Skylake divide.
Could you expand on this, so one won't have to dig out details from elsewhere? > On Cascade Lake and later hardware, guests can now see RDCL_NO (not vulnerable > to Meltdown) amongst others. This causes substantial performance > improvements, as guests are no longer applying software mitigations in cases > where they don't need to. > > Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> > --- > CC: Jan Beulich <jbeul...@suse.com> > CC: Roger Pau Monné <roger....@citrix.com> > CC: Wei Liu <w...@xen.org> > > Not to go in before Roger's libxl changes... I was about to comment on the "now able to", when I saw this. Preferably with a little bit more detail added to the description Reviewed-by: Jan Beulich <jbeul...@suse.com> Jan
