Re: [PATCH v2] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
On 7/3/2020 5:38 AM, Abhishek Bhardwaj wrote: This change adds a new kernel configuration that sets the l1d cache flush setting at compile time rather than at run time. Signed-off-by: Abhishek Bhardwaj --- Changes in v2: - Fix typo in the help of the new KConfig. arch/x86/kernel/cpu/bugs.c | 8 arch/x86/kvm/Kconfig | 17 + 2 files changed, 25 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 0b71970d2d3d2..1dcc875cf5547 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1406,7 +1406,15 @@ enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; #if IS_ENABLED(CONFIG_KVM_INTEL) EXPORT_SYMBOL_GPL(l1tf_mitigation); #endif +#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NEVER; +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_COND; +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_ALWAYS; +#else enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; +#endif how about enum vmx_l1d_flush_state l1tf_vmx_mitigation = #if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1) VMENTER_L1D_FLUSH_NEVER; #elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2) VMENTER_L1D_FLUSH_COND; #elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3) VMENTER_L1D_FLUSH_ALWAYS; #else VMENTER_L1D_FLUSH_AUTO; #endif
Re: [PATCH v2] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
On Thu, Jul 2, 2020 at 3:01 PM Randy Dunlap wrote: > > Hi-- > > On 7/2/20 2:38 PM, Abhishek Bhardwaj wrote: > > This change adds a new kernel configuration that sets the l1d cache > > flush setting at compile time rather than at run time. > > > > Signed-off-by: Abhishek Bhardwaj > > > > --- > > > > Changes in v2: > > - Fix typo in the help of the new KConfig. > > > > arch/x86/kernel/cpu/bugs.c | 8 > > arch/x86/kvm/Kconfig | 17 + > > 2 files changed, 25 insertions(+) > > > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > > index 0b71970d2d3d2..1dcc875cf5547 100644 > > --- a/arch/x86/kernel/cpu/bugs.c > > +++ b/arch/x86/kernel/cpu/bugs.c > > @@ -1406,7 +1406,15 @@ enum l1tf_mitigations l1tf_mitigation > > __ro_after_init = L1TF_MITIGATION_FLUSH; > > #if IS_ENABLED(CONFIG_KVM_INTEL) > > EXPORT_SYMBOL_GPL(l1tf_mitigation); > > #endif > > +#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1) > > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NEVER; > > +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2) > > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_COND; > > +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3) > > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_ALWAYS; > > +#else > > enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; > > +#endif > > EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); > > > > /* > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > > index b277a2db62676..d375dcedd447d 100644 > > --- a/arch/x86/kvm/Kconfig > > +++ b/arch/x86/kvm/Kconfig > > @@ -107,4 +107,21 @@ config KVM_MMU_AUDIT > >This option adds a R/W kVM module parameter 'mmu_audit', which allows > >auditing of KVM MMU events at runtime. > > > > +config KVM_VMENTRY_L1D_FLUSH > > + int "L1D cache flush settings (1-3)" > > + range 1 3 > > + default "2" > > + depends on KVM && X86 && X86_64 > > Why does this apply only to KVM? Sorry, I don't know what this means. The runtime options this aims to emulate applied to kvm driver. Hence, this kernel config applies to KVM ? > > and the "X86 && X86_64" is more than is needed. Just "X86_64" alone > should be enough. Fixed in v3. > > > > + help > > + This setting determines the L1D cache flush behavior before a > > VMENTER. > > + This is similar to setting the option / parameter to > > + kvm-intel.vmentry_l1d_flush. > > + 1 - Never flush. > > + 2 - Conditionally flush. > > + 3 - Always flush. > > + > > +# OK, it's a little counter-intuitive to do this, but it puts it neatly > > under > > +# the virtualization menu. > > +source "drivers/vhost/Kconfig" This was a bad copy paste. Removed in v3. > > > I don't quite understand why this 'source' line is here. > Can you explain more about that, please? > > It puts "VHOST drivers" in the menu 2 times, in 2 totally unrelated > places. Seems like it could be confusing. > > > + > > endif # VIRTUALIZATION > > > -- > ~Randy > -- Abhishek
Re: [PATCH v2] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
Hi-- On 7/2/20 2:38 PM, Abhishek Bhardwaj wrote: > This change adds a new kernel configuration that sets the l1d cache > flush setting at compile time rather than at run time. > > Signed-off-by: Abhishek Bhardwaj > > --- > > Changes in v2: > - Fix typo in the help of the new KConfig. > > arch/x86/kernel/cpu/bugs.c | 8 > arch/x86/kvm/Kconfig | 17 + > 2 files changed, 25 insertions(+) > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > index 0b71970d2d3d2..1dcc875cf5547 100644 > --- a/arch/x86/kernel/cpu/bugs.c > +++ b/arch/x86/kernel/cpu/bugs.c > @@ -1406,7 +1406,15 @@ enum l1tf_mitigations l1tf_mitigation __ro_after_init > = L1TF_MITIGATION_FLUSH; > #if IS_ENABLED(CONFIG_KVM_INTEL) > EXPORT_SYMBOL_GPL(l1tf_mitigation); > #endif > +#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1) > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NEVER; > +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2) > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_COND; > +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3) > +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_ALWAYS; > +#else > enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; > +#endif > EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); > > /* > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index b277a2db62676..d375dcedd447d 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -107,4 +107,21 @@ config KVM_MMU_AUDIT >This option adds a R/W kVM module parameter 'mmu_audit', which allows >auditing of KVM MMU events at runtime. > > +config KVM_VMENTRY_L1D_FLUSH > + int "L1D cache flush settings (1-3)" > + range 1 3 > + default "2" > + depends on KVM && X86 && X86_64 Why does this apply only to KVM? and the "X86 && X86_64" is more than is needed. Just "X86_64" alone should be enough. > + help > + This setting determines the L1D cache flush behavior before a VMENTER. > + This is similar to setting the option / parameter to > + kvm-intel.vmentry_l1d_flush. > + 1 - Never flush. > + 2 - Conditionally flush. > + 3 - Always flush. > + > +# OK, it's a little counter-intuitive to do this, but it puts it neatly under > +# the virtualization menu. > +source "drivers/vhost/Kconfig" I don't quite understand why this 'source' line is here. Can you explain more about that, please? It puts "VHOST drivers" in the menu 2 times, in 2 totally unrelated places. Seems like it could be confusing. > + > endif # VIRTUALIZATION -- ~Randy
[PATCH v2] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
This change adds a new kernel configuration that sets the l1d cache flush setting at compile time rather than at run time. Signed-off-by: Abhishek Bhardwaj --- Changes in v2: - Fix typo in the help of the new KConfig. arch/x86/kernel/cpu/bugs.c | 8 arch/x86/kvm/Kconfig | 17 + 2 files changed, 25 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 0b71970d2d3d2..1dcc875cf5547 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1406,7 +1406,15 @@ enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; #if IS_ENABLED(CONFIG_KVM_INTEL) EXPORT_SYMBOL_GPL(l1tf_mitigation); #endif +#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NEVER; +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_COND; +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3) +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_ALWAYS; +#else enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; +#endif EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); /* diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index b277a2db62676..d375dcedd447d 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -107,4 +107,21 @@ config KVM_MMU_AUDIT This option adds a R/W kVM module parameter 'mmu_audit', which allows auditing of KVM MMU events at runtime. +config KVM_VMENTRY_L1D_FLUSH + int "L1D cache flush settings (1-3)" + range 1 3 + default "2" + depends on KVM && X86 && X86_64 + help +This setting determines the L1D cache flush behavior before a VMENTER. +This is similar to setting the option / parameter to +kvm-intel.vmentry_l1d_flush. +1 - Never flush. +2 - Conditionally flush. +3 - Always flush. + +# OK, it's a little counter-intuitive to do this, but it puts it neatly under +# the virtualization menu. +source "drivers/vhost/Kconfig" + endif # VIRTUALIZATION -- 2.27.0.212.ge8ba1cc988-goog
