Il 21/08/2014 10:05, Wanpeng Li ha scritto: > Hi Nadav, > On Wed, Aug 20, 2014 at 03:11:51PM +0300, Nadav Amit wrote: >> Currently, when an msr is updated using kvm_set_shared_msr the masked bits >> are >> zeroed. This behavior is currently valid since the only MSR with partial >> mask > > Why zeroed? vmx_vcpu_setup() set all mask to -1ull.
He meant they are passed as zero in the WRMSR but actually they're not zeroed. They're set to the value that is passed to kvm_set_shared_msr, and this value is massaged elsewhere to do mix guest and host bugs. See update_transition_efer. So I'm removing this patch, it's wrong. Paolo >> is EFER, in which only SCE might be unmasked. However, using the > > Do you mean SCE might be masked? > >> kvm_set_shared_msr for other purposes becomes impossible. >> >> This patch keeps the masked bits unmodified while setting a shared msr. >> > > Do you mean "keeps the unmasked bits unmodified" instead of "keeps the > masked bits unmodified"? > > Regards, > Wanpeng Li > >> Signed-off-by: Nadav Amit <[email protected]> >> --- >> arch/x86/kvm/x86.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 5f5edb6..ee42410 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -236,6 +236,7 @@ void kvm_set_shared_msr(unsigned slot, u64 value, u64 >> mask) >> >> if (((value ^ smsr->values[slot].curr) & mask) == 0) >> return; >> + value = (smsr->values[slot].curr & ~mask) | (value & mask); >> smsr->values[slot].curr = value; >> wrmsrl(shared_msrs_global.msrs[slot], value); >> if (!smsr->registered) { >> -- >> 1.9.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
