* [PATCH] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
@ 2020-07-02 16:19 Abhishek Bhardwaj
2020-07-06 15:01 ` mark gross
0 siblings, 1 reply; 2+ messages in thread
From: Abhishek Bhardwaj @ 2020-07-02 16:19 UTC (permalink / raw)
To: LKML
Cc: Abhishek Bhardwaj, Anthony Steinhauser, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jim Mattson, Joerg Roedel,
Josh Poimboeuf, Mark Gross, Paolo Bonzini, Pawan Gupta,
Peter Zijlstra, Sean Christopherson, Thomas Gleixner, Tony Luck,
Vitaly Kuznetsov, Waiman Long, Wanpeng Li, kvm, x86
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 <abhishekbh@google.com>
---
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..f82a0c564e931 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 - Conditinally 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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode
2020-07-02 16:19 [PATCH] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode Abhishek Bhardwaj
@ 2020-07-06 15:01 ` mark gross
0 siblings, 0 replies; 2+ messages in thread
From: mark gross @ 2020-07-06 15:01 UTC (permalink / raw)
To: Abhishek Bhardwaj
Cc: LKML, Anthony Steinhauser, Borislav Petkov, H. Peter Anvin,
Ingo Molnar, Jim Mattson, Joerg Roedel, Josh Poimboeuf,
Paolo Bonzini, Pawan Gupta, Peter Zijlstra, Sean Christopherson,
Thomas Gleixner, Tony Luck, Vitaly Kuznetsov, Waiman Long,
Wanpeng Li, kvm, x86
On Thu, Jul 02, 2020 at 09:19:16AM -0700, 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.
Why is this desired?
--mark
>
> Signed-off-by: Abhishek Bhardwaj <abhishekbh@google.com>
> ---
>
> 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..f82a0c564e931 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 - Conditinally 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
>
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2020-07-06 15:01 ` mark gross
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