78 lines
2.5 KiB
Diff
78 lines
2.5 KiB
Diff
From foo@baz Mon May 21 21:56:07 CEST 2018
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 10 May 2018 20:42:48 +0200
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Subject: x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
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From: Thomas Gleixner <tglx@linutronix.de>
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commit 47c61b3955cf712cadfc25635bf9bc174af030ea upstream
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Add the necessary logic for supporting the emulated VIRT_SPEC_CTRL MSR to
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x86_virt_spec_ctrl(). If either X86_FEATURE_LS_CFG_SSBD or
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X86_FEATURE_VIRT_SPEC_CTRL is set then use the new guest_virt_spec_ctrl
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argument to check whether the state must be modified on the host. The
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update reuses speculative_store_bypass_update() so the ZEN-specific sibling
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coordination can be reused.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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arch/x86/include/asm/spec-ctrl.h | 6 ++++++
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arch/x86/kernel/cpu/bugs.c | 30 ++++++++++++++++++++++++++++++
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2 files changed, 36 insertions(+)
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--- a/arch/x86/include/asm/spec-ctrl.h
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+++ b/arch/x86/include/asm/spec-ctrl.h
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@@ -53,6 +53,12 @@ static inline u64 ssbd_tif_to_spec_ctrl(
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return (tifn & _TIF_SSBD) >> (TIF_SSBD - SPEC_CTRL_SSBD_SHIFT);
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}
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+static inline unsigned long ssbd_spec_ctrl_to_tif(u64 spec_ctrl)
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+{
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+ BUILD_BUG_ON(TIF_SSBD < SPEC_CTRL_SSBD_SHIFT);
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+ return (spec_ctrl & SPEC_CTRL_SSBD) << (TIF_SSBD - SPEC_CTRL_SSBD_SHIFT);
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+}
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+
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static inline u64 ssbd_tif_to_amd_ls_cfg(u64 tifn)
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{
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return (tifn & _TIF_SSBD) ? x86_amd_ls_cfg_ssbd_mask : 0ULL;
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -162,6 +162,36 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl,
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wrmsrl(MSR_IA32_SPEC_CTRL, msrval);
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}
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}
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+
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+ /*
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+ * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
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+ * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
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+ */
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+ if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
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+ !static_cpu_has(X86_FEATURE_VIRT_SSBD))
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+ return;
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+
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+ /*
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+ * If the host has SSBD mitigation enabled, force it in the host's
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+ * virtual MSR value. If its not permanently enabled, evaluate
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+ * current's TIF_SSBD thread flag.
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+ */
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+ if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
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+ hostval = SPEC_CTRL_SSBD;
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+ else
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+ hostval = ssbd_tif_to_spec_ctrl(ti->flags);
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+
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+ /* Sanitize the guest value */
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+ guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
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+
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+ if (hostval != guestval) {
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+ unsigned long tif;
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+
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+ tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
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+ ssbd_spec_ctrl_to_tif(hostval);
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+
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+ speculative_store_bypass_update(tif);
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+ }
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}
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EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);
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