2017-11-08 14:32+0200, Eyal Moscovici: > Some guests use these unhandled MSRs very frequently. > This cause dmesg to be populated with lots of aggregated messages on > usage of ignored MSRs. As ignore_msrs=true means that the user is > well-aware his guest use ignored MSRs, allow to also disable the > prints on their usage. > > An example of such guest is ESXi which tends to access a lot to MSR > 0x34 (MSR_SMI_COUNT) very frequently. > > In addition, we have observed this to cause unnecessary delays to > guest execution. Such an example is ESXi which experience networking > delays in it's guests (L2 guests) because of these prints (even when > prints are rate-limited). This can easily be reproduced by pinging > from one L2 guest to another. Once in a while, a peak in ping RTT > will be observed. Removing these unhandled MSR prints solves the > issue. > > Because these prints can help diagnose issues with guests, > this commit only suppress them by a module parameter instead of > removing them from code entirely. > > Signed-off-by: Eyal Moscovici <eyal.moscovici@xxxxxxxxxx> > Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx> > Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx> > Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 03869eb..21c0059 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -107,6 +107,9 @@ > static bool __read_mostly ignore_msrs = 0; > module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR); > > +static bool __read_mostly suppress_ignore_msrs_prints = false; > +module_param(suppress_ignore_msrs_prints, bool, S_IRUGO | S_IWUSR); What about calling it 'print_ignored_msrs' and default to true? (I can change that when applying.) Thanks.
