On 04/09/2020 09:36, Jan Beulich wrote: > On 01.09.2020 12:54, Roger Pau Monne wrote: >> The SYSCFG, TOP_MEM1 and TOP_MEM2 MSRs are currently exposed to guests >> and writes are silently discarded. Make this explicit in the SVM code >> now, and just return default constant values when attempting to read >> any of the MSRs, while continuing to silently drop writes. >> >> Signed-off-by: Roger Pau Monné <roger....@citrix.com> > Reviewed-by: Jan Beulich <jbeul...@suse.com> > >> --- a/xen/arch/x86/hvm/svm/svm.c >> +++ b/xen/arch/x86/hvm/svm/svm.c >> @@ -1917,6 +1917,9 @@ static int svm_msr_read_intercept(unsigned int msr, >> uint64_t *msr_content) >> goto gpf; >> break; >> >> + case MSR_K8_SYSCFG: >> + case MSR_K8_TOP_MEM1: >> + case MSR_K8_TOP_MEM2: >> case MSR_K8_VM_CR: >> *msr_content = 0; >> break; > Andrew, since you did suggest otherwise before, may I ask for an > explicit statement of yours here, be it in ack/nak form or something > less formal?
I'm not entirely convinced it is a safe thing to do, but lets see what happens. There is likely to be a bug tail from the flipping the default behaviour at the end of the series, and this is certainly a simpler set of logic than the alternative. ~Andrew
