From: Tim Chen <tim.c.chen@linux.intel.com>
To: Jiri Kosina <jikos@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Casey Schaufler <casey.schaufler@intel.com>,
Asit Mallick <asit.k.mallick@intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
Jon Masters <jcm@redhat.com>, Waiman Long <longman9394@gmail.com>,
Greg KH <gregkh@linuxfoundation.org>,
Dave Stewart <david.c.stewart@intel.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
stable@vger.kernel.org
Subject: [Patch v6 05/16] x86/speculation: Reorganize speculation control MSRs update
Date: Tue, 20 Nov 2018 15:59:57 -0800 [thread overview]
Message-ID: <7c2334e74794e31f01cbfec1d14bc081745436a1.1542757030.git.tim.c.chen@linux.intel.com> (raw)
In-Reply-To: <cover.1542757030.git.tim.c.chen@linux.intel.com>
In-Reply-To: <cover.1542757030.git.tim.c.chen@linux.intel.com>
The logic to detect whether there's a change in the previous
and next task's flag relevant to update speculation control
MSRs are spread out across multiple functions.
Consolidate all checks needed for updating speculation
control MSRs to __speculation_ctrl_update().
This makes it easy to pick the right speculation control MSR,
and the bits in the MSR that needs updating based on
TIF flags changes.
Originally-by: Thomas Lendacky <Thomas.Lendacky@amd.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
arch/x86/kernel/process.c | 44 +++++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 8aa4960..74bef48 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -397,25 +397,48 @@ static __always_inline void amd_set_ssb_virt_state(unsigned long tifn)
static __always_inline void spec_ctrl_update_msr(unsigned long tifn)
{
- u64 msr = x86_spec_ctrl_base | ssbd_tif_to_spec_ctrl(tifn);
+ u64 msr = x86_spec_ctrl_base;
+
+ /*
+ * If X86_FEATURE_SSBD is not set, the SSBD
+ * bit is not to be touched.
+ */
+ if (static_cpu_has(X86_FEATURE_SSBD))
+ msr |= ssbd_tif_to_spec_ctrl(tifn);
wrmsrl(MSR_IA32_SPEC_CTRL, msr);
}
-static __always_inline void __speculation_ctrl_update(unsigned long tifn)
-{
- if (static_cpu_has(X86_FEATURE_VIRT_SSBD))
- amd_set_ssb_virt_state(tifn);
- else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD))
- amd_set_core_ssb_state(tifn);
- else
+/*
+ * Update the MSRs managing speculation control during context switch.
+ *
+ * tifp: previous task's thread flags
+ * tifn: next task's thread flags
+ */
+static __always_inline void __speculation_ctrl_update(unsigned long tifp,
+ unsigned long tifn)
+{
+ bool updmsr = false;
+
+ /* If TIF_SSBD is different, select the proper mitigation method */
+ if ((tifp ^ tifn) & _TIF_SSBD) {
+ if (static_cpu_has(X86_FEATURE_VIRT_SSBD))
+ amd_set_ssb_virt_state(tifn);
+ else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD))
+ amd_set_core_ssb_state(tifn);
+ else if (static_cpu_has(X86_FEATURE_SSBD))
+ updmsr = true;
+ }
+
+ if (updmsr)
spec_ctrl_update_msr(tifn);
}
void speculation_ctrl_update(unsigned long tif)
{
+ /* Forced update. Make sure all relevant TIF flags are different */
preempt_disable();
- __speculation_ctrl_update(tif);
+ __speculation_ctrl_update(~tif, tif);
preempt_enable();
}
@@ -451,8 +474,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
if ((tifp ^ tifn) & _TIF_NOCPUID)
set_cpuid_faulting(!!(tifn & _TIF_NOCPUID));
- if ((tifp ^ tifn) & _TIF_SSBD)
- __speculation_ctrl_update(tifn);
+ __speculation_ctrl_update(tifp, tifn);
}
/*
--
2.9.4
next prev parent reply other threads:[~2018-11-21 0:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 23:59 [Patch v6 00/16] Provide task property based options to enable Spectre v2 userspace-userspace protection Tim Chen
2018-11-20 23:59 ` [Patch v6 01/16] x86/speculation: Reorganize cpu_show_common() Tim Chen
2018-11-20 23:59 ` [Patch v6 02/16] x86/speculation: Add X86_FEATURE_USE_IBRS_ENHANCED Tim Chen
2018-11-20 23:59 ` [Patch v6 03/16] x86/speculation: Disable STIBP when enhanced IBRS is in use Tim Chen
2018-11-20 23:59 ` [Patch v6 04/16] x86/speculation: Rename SSBD update functions Tim Chen
2018-11-20 23:59 ` Tim Chen [this message]
2018-11-20 23:59 ` [Patch v6 06/16] smt: Create cpu_smt_enabled static key for SMT specific code Tim Chen
2018-11-20 23:59 ` [Patch v6 07/16] x86/smt: Convert cpu_smt_control check to cpu_smt_enabled static key Tim Chen
2018-11-21 0:00 ` [Patch v6 08/16] x86/speculation: Turn on or off STIBP according to a task's TIF_STIBP Tim Chen
2018-11-21 0:00 ` [Patch v6 09/16] x86/speculation: Add Spectre v2 app to app protection modes Tim Chen
2018-11-21 0:00 ` [Patch v6 10/16] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Tim Chen
2018-11-21 0:00 ` [Patch v6 11/16] x86/speculation: Enable IBPB for tasks with TIF_SPEC_BRANCH_SPECULATION Tim Chen
2018-11-21 0:00 ` [Patch v6 12/16] x86/speculation: Add 'seccomp' Spectre v2 app to app protection mode Tim Chen
2018-11-21 0:44 ` Jiri Kosina
2018-11-21 0:54 ` Tim Chen
2018-11-21 0:00 ` [Patch v6 13/16] security: Update speculation restriction of a process when modifying its dumpability Tim Chen
2018-11-21 0:00 ` [Patch v6 14/16] x86/speculation: Use STIBP to restrict speculation on non-dumpable task Tim Chen
2018-11-21 1:27 ` Linus Torvalds
2018-11-21 6:14 ` Jiri Kosina
2018-11-21 17:41 ` Tim Chen
2018-11-21 19:32 ` Linus Torvalds
2018-11-21 20:07 ` Dave Hansen
2018-11-21 20:26 ` Linus Torvalds
2018-11-21 0:00 ` [Patch v6 15/16] sched/smt: Make sched_smt_present track topology Tim Chen
2018-11-21 0:00 ` [Patch v6 16/16] x86/smt: Allow disabling of SMT when last SMT is offlined Tim Chen
2018-11-21 0:44 ` [Patch v6 00/16] Provide task property based options to enable Spectre v2 userspace-userspace protection Tim Chen
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