>>> On 02.07.18 at 11:57, <andrew.coop...@citrix.com> wrote: > These MSRs are non-architectural and the available booleans were used in lieu > of an architectural signal of availability. The MSRs are unconditionally > available to HVM guests, but currently for PV guests, are hidden when CPUID > faulting is unavailable. > > However, in hindsight, the additional booleans make toolstack MSR interactions > more complicated. As the behaviour of the MSRs is reserved when unavailable,
Is it? Isn't the expected (mandated?) behavior raising of #GP(0) in that case? > unconditionally letting the MSRs be accessible is compatible behaviour, even > for PV guests. > > The new behaviour is: > * PLATFORM_INFO is unconditionally readable even for PV guests and will > indicate the presense or absense of CPUID Faulting in bit 31. > * MISC_FEATURES_ENABLES is uncondtionally readable, and bit 0 may be set iff > PLATFORM_INFO reports that CPUID Faulting is available. For these two I agree with the intended new behavior though (despite seeing a tiny bit of a risk); I merely think the statement above is a little too broad. > Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> Reviewed-by: Jan Beulich <jbeul...@suse.com> Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
