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authorThomas Gleixner <tglx@linutronix.de>2018-05-10 20:42:48 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 18:54:06 +0200
commit3f44c1a3c29379aa976be27df1da0fc4b9e7c364 (patch)
treeafc86b0ccd0c8012cc5a147de3818cfcbb119192
parent71179d5dcbb96afc70c3344fd4b35db0c33d6008 (diff)
x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
commit 47c61b3955cf712cadfc25635bf9bc174af030ea upstream Add the necessary logic for supporting the emulated VIRT_SPEC_CTRL MSR to x86_virt_spec_ctrl(). If either X86_FEATURE_LS_CFG_SSBD or X86_FEATURE_VIRT_SPEC_CTRL is set then use the new guest_virt_spec_ctrl argument to check whether the state must be modified on the host. The update reuses speculative_store_bypass_update() so the ZEN-specific sibling coordination can be reused. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/include/asm/spec-ctrl.h6
-rw-r--r--arch/x86/kernel/cpu/bugs.c30
2 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/include/asm/spec-ctrl.h b/arch/x86/include/asm/spec-ctrl.h
index 763d49710329..ae7c2c5cd7f0 100644
--- a/arch/x86/include/asm/spec-ctrl.h
+++ b/arch/x86/include/asm/spec-ctrl.h
@@ -53,6 +53,12 @@ static inline u64 ssbd_tif_to_spec_ctrl(u64 tifn)
return (tifn & _TIF_SSBD) >> (TIF_SSBD - SPEC_CTRL_SSBD_SHIFT);
}
+static inline unsigned long ssbd_spec_ctrl_to_tif(u64 spec_ctrl)
+{
+ BUILD_BUG_ON(TIF_SSBD < SPEC_CTRL_SSBD_SHIFT);
+ return (spec_ctrl & SPEC_CTRL_SSBD) << (TIF_SSBD - SPEC_CTRL_SSBD_SHIFT);
+}
+
static inline u64 ssbd_tif_to_amd_ls_cfg(u64 tifn)
{
return (tifn & _TIF_SSBD) ? x86_amd_ls_cfg_ssbd_mask : 0ULL;
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 8e327bfec513..7416fc206b4a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -162,6 +162,36 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
wrmsrl(MSR_IA32_SPEC_CTRL, msrval);
}
}
+
+ /*
+ * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
+ * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
+ */
+ if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
+ !static_cpu_has(X86_FEATURE_VIRT_SSBD))
+ return;
+
+ /*
+ * If the host has SSBD mitigation enabled, force it in the host's
+ * virtual MSR value. If its not permanently enabled, evaluate
+ * current's TIF_SSBD thread flag.
+ */
+ if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
+ hostval = SPEC_CTRL_SSBD;
+ else
+ hostval = ssbd_tif_to_spec_ctrl(ti->flags);
+
+ /* Sanitize the guest value */
+ guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
+
+ if (hostval != guestval) {
+ unsigned long tif;
+
+ tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
+ ssbd_spec_ctrl_to_tif(hostval);
+
+ speculative_store_bypass_update(tif);
+ }
}
EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);