On Fri, May 02, 2025 at 05:03:43AM +0000, Manali Shukla wrote: > Misbehaving guests can cause bus locks to degrade the performance of > the system. The Bus Lock Threshold feature can be used to address this > issue by providing capability to the hypervisor to limit guest's > ability to generate bus lock, thereby preventing system slowdown due > to performance penalities. > > When the Bus Lock Threshold feature is enabled, the processor checks > the bus lock threshold count before executing the buslock and decides > whether to trigger bus lock exit or not. > > The value of the bus lock threshold count '0' generates bus lock > exits, and if the value is greater than '0', the bus lock is executed > successfully and the bus lock threshold count is decremented. > > Presence of the Bus Lock threshold feature is indicated via CPUID > function 0x8000000A_EDX[29]. > > Signed-off-by: Manali Shukla <[email protected]> > --- > arch/x86/include/asm/cpufeatures.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/include/asm/cpufeatures.h > b/arch/x86/include/asm/cpufeatures.h > index e95a8e9ef22b..b51f3ce84032 100644 > --- a/arch/x86/include/asm/cpufeatures.h > +++ b/arch/x86/include/asm/cpufeatures.h > @@ -378,6 +378,7 @@ > #define X86_FEATURE_V_SPEC_CTRL (15*32+20) /* "v_spec_ctrl" > Virtual SPEC_CTRL */ > #define X86_FEATURE_VNMI (15*32+25) /* "vnmi" Virtual NMI */ > #define X86_FEATURE_SVME_ADDR_CHK (15*32+28) /* SVME addr check */ > +#define X86_FEATURE_BUS_LOCK_THRESHOLD (15*32+29) /* Bus lock > threshold */ > #define X86_FEATURE_IDLE_HLT (15*32+30) /* IDLE HLT intercept */ > > /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */ > --
Reviewed-by: Borislav Petkov (AMD) <[email protected]> -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
