From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "Andy Lutomirski" <luto@kernel.org>, "Dave Hansen" <dave.hansen@intel.com>, "Tony Luck" <tony.luck@intel.com>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Joerg Roedel" <joro@8bytes.org>, Josh Poimboeuf <jpoimboe@redhat.com>, "Dave Jiang" <dave.jiang@intel.com>, "Jacob Jun Pan" <jacob.jun.pan@intel.com>, "Ashok Raj" <ashok.raj@intel.com>, "Ravi V Shankar" <ravi.v.shankar@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com>, iommu@lists.linux-foundation.org, x86 <x86@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org> Subject: [PATCH 2/8] x86/process: Clear PASID state for a newly forked/cloned thread Date: Mon, 20 Sep 2021 19:23:43 +0000 [thread overview] Message-ID: <20210920192349.2602141-3-fenghua.yu@intel.com> (raw) In-Reply-To: <20210920192349.2602141-1-fenghua.yu@intel.com> The PASID state has to be cleared on forks, since the child has a different address space. The PASID is also cleared for thread clone. While it would be correct to inherit the PASID in this case, it is unknown whether the new task will use ENQCMD. Giving it the PASID "just in case" would have the downside of increased context switch overhead to setting the PASID MSR and losing init optimization. Since #GP faults have to be handled on any threads that were created before the PASID was assigned to the mm of the process, newly created threads might as well be treated in a consistent way. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- arch/x86/kernel/process.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1d9463e3096b..c713986ef7d7 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -154,6 +154,14 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, frame->flags = X86_EFLAGS_FIXED; #endif + if (static_cpu_has(X86_FEATURE_ENQCMD)) { + /* + * Clear the PASID bit in xfeatures so that the PASID MSR + * will be initialized as init state (0). + */ + p->thread.fpu.state.xsave.header.xfeatures &= ~XFEATURE_MASK_PASID; + } + /* Kernel thread ? */ if (unlikely(p->flags & PF_KTHREAD)) { p->thread.pkru = pkru_get_init_value(); -- 2.33.0 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "Andy Lutomirski" <luto@kernel.org>, "Dave Hansen" <dave.hansen@intel.com>, "Tony Luck" <tony.luck@intel.com>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Joerg Roedel" <joro@8bytes.org>, Josh Poimboeuf <jpoimboe@redhat.com>, "Dave Jiang" <dave.jiang@intel.com>, "Jacob Jun Pan" <jacob.jun.pan@intel.com>, "Ashok Raj" <ashok.raj@intel.com>, "Ravi V Shankar" <ravi.v.shankar@intel.com> Cc: iommu@lists.linux-foundation.org, "x86" <x86@kernel.org>, "linux-kernel" <linux-kernel@vger.kernel.org>, Fenghua Yu <fenghua.yu@intel.com> Subject: [PATCH 2/8] x86/process: Clear PASID state for a newly forked/cloned thread Date: Mon, 20 Sep 2021 19:23:43 +0000 [thread overview] Message-ID: <20210920192349.2602141-3-fenghua.yu@intel.com> (raw) In-Reply-To: <20210920192349.2602141-1-fenghua.yu@intel.com> The PASID state has to be cleared on forks, since the child has a different address space. The PASID is also cleared for thread clone. While it would be correct to inherit the PASID in this case, it is unknown whether the new task will use ENQCMD. Giving it the PASID "just in case" would have the downside of increased context switch overhead to setting the PASID MSR and losing init optimization. Since #GP faults have to be handled on any threads that were created before the PASID was assigned to the mm of the process, newly created threads might as well be treated in a consistent way. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- arch/x86/kernel/process.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1d9463e3096b..c713986ef7d7 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -154,6 +154,14 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, frame->flags = X86_EFLAGS_FIXED; #endif + if (static_cpu_has(X86_FEATURE_ENQCMD)) { + /* + * Clear the PASID bit in xfeatures so that the PASID MSR + * will be initialized as init state (0). + */ + p->thread.fpu.state.xsave.header.xfeatures &= ~XFEATURE_MASK_PASID; + } + /* Kernel thread ? */ if (unlikely(p->flags & PF_KTHREAD)) { p->thread.pkru = pkru_get_init_value(); -- 2.33.0
next prev parent reply other threads:[~2021-09-20 20:02 UTC|newest] Thread overview: 154+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-20 19:23 [PATCH 0/8] Re-enable ENQCMD and PASID MSR Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-20 19:23 ` [PATCH 1/8] iommu/vt-d: Clean up unused PASID updating functions Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-29 7:34 ` Lu Baolu 2021-09-29 7:34 ` Lu Baolu 2021-09-30 0:40 ` Fenghua Yu 2021-09-30 0:40 ` Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu [this message] 2021-09-20 19:23 ` [PATCH 2/8] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu 2021-09-20 19:23 ` [PATCH 3/8] sched: Define and initialize a flag to identify valid PASID in the task Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-20 19:23 ` [PATCH 4/8] x86/traps: Demand-populate PASID MSR via #GP Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-22 21:07 ` Peter Zijlstra 2021-09-22 21:07 ` Peter Zijlstra 2021-09-22 21:11 ` Peter Zijlstra 2021-09-22 21:11 ` Peter Zijlstra 2021-09-22 21:26 ` Luck, Tony 2021-09-22 21:26 ` Luck, Tony 2021-09-23 7:03 ` Peter Zijlstra 2021-09-23 7:03 ` Peter Zijlstra 2021-09-22 21:33 ` Dave Hansen 2021-09-22 21:33 ` Dave Hansen 2021-09-23 7:05 ` Peter Zijlstra 2021-09-23 7:05 ` Peter Zijlstra 2021-09-22 21:36 ` Fenghua Yu 2021-09-22 21:36 ` Fenghua Yu 2021-09-22 23:39 ` Fenghua Yu 2021-09-22 23:39 ` Fenghua Yu 2021-09-23 17:14 ` Luck, Tony 2021-09-23 17:14 ` Luck, Tony 2021-09-24 13:37 ` Peter Zijlstra 2021-09-24 13:37 ` Peter Zijlstra 2021-09-24 15:39 ` Luck, Tony 2021-09-24 15:39 ` Luck, Tony 2021-09-29 9:00 ` Peter Zijlstra 2021-09-29 9:00 ` Peter Zijlstra 2021-09-23 11:31 ` Thomas Gleixner 2021-09-23 11:31 ` Thomas Gleixner 2021-09-23 23:17 ` Andy Lutomirski 2021-09-23 23:17 ` Andy Lutomirski 2021-09-24 2:56 ` Fenghua Yu 2021-09-24 2:56 ` Fenghua Yu 2021-09-24 5:12 ` Andy Lutomirski 2021-09-24 5:12 ` Andy Lutomirski 2021-09-27 21:02 ` Luck, Tony 2021-09-27 21:02 ` Luck, Tony 2021-09-27 23:51 ` Dave Hansen 2021-09-27 23:51 ` Dave Hansen 2021-09-28 18:50 ` Luck, Tony 2021-09-28 18:50 ` Luck, Tony 2021-09-28 19:19 ` Dave Hansen 2021-09-28 19:19 ` Dave Hansen 2021-09-28 20:28 ` Luck, Tony 2021-09-28 20:28 ` Luck, Tony 2021-09-28 20:55 ` Dave Hansen 2021-09-28 20:55 ` Dave Hansen 2021-09-28 23:10 ` Luck, Tony 2021-09-28 23:10 ` Luck, Tony 2021-09-28 23:50 ` Fenghua Yu 2021-09-28 23:50 ` Fenghua Yu 2021-09-29 0:08 ` Luck, Tony 2021-09-29 0:08 ` Luck, Tony 2021-09-29 0:26 ` Yu, Fenghua 2021-09-29 0:26 ` Yu, Fenghua 2021-09-29 1:06 ` Luck, Tony 2021-09-29 1:06 ` Luck, Tony 2021-09-29 1:16 ` Fenghua Yu 2021-09-29 1:16 ` Fenghua Yu 2021-09-29 2:11 ` Luck, Tony 2021-09-29 2:11 ` Luck, Tony 2021-09-29 1:56 ` Yu, Fenghua 2021-09-29 1:56 ` Yu, Fenghua 2021-09-29 2:15 ` Luck, Tony 2021-09-29 2:15 ` Luck, Tony 2021-09-29 16:58 ` Andy Lutomirski 2021-09-29 16:58 ` Andy Lutomirski 2021-09-29 17:07 ` Luck, Tony 2021-09-29 17:07 ` Luck, Tony 2021-09-29 17:48 ` Andy Lutomirski 2021-09-29 17:48 ` Andy Lutomirski 2021-09-20 19:23 ` [PATCH 5/8] x86/mmu: Add mm-based PASID refcounting Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-23 5:43 ` Lu Baolu 2021-09-23 5:43 ` Lu Baolu 2021-09-30 0:44 ` Fenghua Yu 2021-09-30 0:44 ` Fenghua Yu 2021-09-23 14:36 ` Thomas Gleixner 2021-09-23 14:36 ` Thomas Gleixner 2021-09-23 16:40 ` Luck, Tony 2021-09-23 16:40 ` Luck, Tony 2021-09-23 17:48 ` Thomas Gleixner 2021-09-23 17:48 ` Thomas Gleixner 2021-09-24 13:18 ` Thomas Gleixner 2021-09-24 13:18 ` Thomas Gleixner 2021-09-24 16:12 ` Luck, Tony 2021-09-24 16:12 ` Luck, Tony 2021-09-24 23:03 ` Andy Lutomirski 2021-09-24 23:03 ` Andy Lutomirski 2021-09-24 23:11 ` Luck, Tony 2021-09-24 23:11 ` Luck, Tony 2021-09-29 9:54 ` Peter Zijlstra 2021-09-29 9:54 ` Peter Zijlstra 2021-09-29 12:28 ` Thomas Gleixner 2021-09-29 12:28 ` Thomas Gleixner 2021-09-29 16:51 ` Luck, Tony 2021-09-29 16:51 ` Luck, Tony 2021-09-29 17:07 ` Fenghua Yu 2021-09-29 17:07 ` Fenghua Yu 2021-09-29 16:59 ` Andy Lutomirski 2021-09-29 16:59 ` Andy Lutomirski 2021-09-29 17:15 ` Thomas Gleixner 2021-09-29 17:15 ` Thomas Gleixner 2021-09-29 17:41 ` Luck, Tony 2021-09-29 17:41 ` Luck, Tony 2021-09-29 17:46 ` Andy Lutomirski 2021-09-29 17:46 ` Andy Lutomirski 2021-09-29 18:07 ` Fenghua Yu 2021-09-29 18:07 ` Fenghua Yu 2021-09-29 18:31 ` Luck, Tony 2021-09-29 18:31 ` Luck, Tony 2021-09-29 20:07 ` Thomas Gleixner 2021-09-29 20:07 ` Thomas Gleixner 2021-09-24 16:12 ` Fenghua Yu 2021-09-24 16:12 ` Fenghua Yu 2021-09-25 23:13 ` Thomas Gleixner 2021-09-25 23:13 ` Thomas Gleixner 2021-09-28 16:36 ` Fenghua Yu 2021-09-28 16:36 ` Fenghua Yu 2021-09-23 23:09 ` Andy Lutomirski 2021-09-23 23:09 ` Andy Lutomirski 2021-09-23 23:22 ` Luck, Tony 2021-09-23 23:22 ` Luck, Tony 2021-09-24 5:17 ` Andy Lutomirski 2021-09-24 5:17 ` Andy Lutomirski 2021-09-20 19:23 ` [PATCH 6/8] x86/cpufeatures: Re-enable ENQCMD Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-20 19:23 ` [PATCH 7/8] tools/objtool: Check for use of the ENQCMD instruction in the kernel Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu 2021-09-22 21:03 ` Peter Zijlstra 2021-09-22 21:03 ` Peter Zijlstra 2021-09-22 23:44 ` Fenghua Yu 2021-09-22 23:44 ` Fenghua Yu 2021-09-23 7:17 ` Peter Zijlstra 2021-09-23 7:17 ` Peter Zijlstra 2021-09-23 15:26 ` Fenghua Yu 2021-09-23 15:26 ` Fenghua Yu 2021-09-24 0:55 ` Josh Poimboeuf 2021-09-24 0:55 ` Josh Poimboeuf 2021-09-24 0:57 ` Fenghua Yu 2021-09-24 0:57 ` Fenghua Yu 2021-09-20 19:23 ` [PATCH 8/8] docs: x86: Change documentation for SVA (Shared Virtual Addressing) Fenghua Yu 2021-09-20 19:23 ` Fenghua Yu
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