From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "Andy Lutomirski" <luto@kernel.org>, "Tony Luck" <tony.luck@intel.com>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Joerg Roedel" <joro@8bytes.org>, Josh Poimboeuf <jpoimboe@redhat.com>, "Jacob Pan" <jacob.jun.pan@linux.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 v4 06/11] x86/fpu: Clear PASID when copying fpstate Date: Mon, 7 Feb 2022 15:02:49 -0800 [thread overview] Message-ID: <20220207230254.3342514-7-fenghua.yu@intel.com> (raw) In-Reply-To: <20220207230254.3342514-1-fenghua.yu@intel.com> The kernel must allocate a Process Address Space ID (PASID) on behalf of each process which will use ENQCMD and program it into the new MSR to communicate the process identity to platform hardware. ENQCMD uses the PASID stored in this MSR to tag requests from this process. The PASID state must be cleared on fork() since fork creates a new address space. For clone(), it would be functionally OK to copy the PASID. However, clearing it is _also_ functionally OK since any PASID use will trigger the #GP handler to populate the MSR. Copying the PASID state has two main downsides: * It requires differentiating fork() and clone() in the code, both in the FPU code and keeping tsk->pasid_activated consistent. * It guarantees that the PASID is out of its init state, which incurs small but non-zero cost on every XSAVE/XRSTOR. The main downside of clearing the PASID at fpstate copy is the future, one-time #GP for the thread. Use the simplest approach: clear the PASID state both on clone() and fork(). Rely on the #GP handler for MSR population in children. Also, just clear the PASID bit from xfeatures if XSAVE is supported. This will have no effect on systems that do not have PASID support. It is virtually zero overhead because 'dst_fpu' was just written and the whole thing is cache hot. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- v4: - Add "Reviewed-by: Thomas Gleixner <tglx@linutronix.de>" (Thomas). v2: - Rewrite changelog (Dave Hansen). - Move xfeature tweaking into fpu_clone() and make it unconditional if XSAVE is supported (Dave Hansen). arch/x86/kernel/fpu/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 8dea01ffc5c1..19821f027cb3 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -612,6 +612,13 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags) fpu_inherit_perms(dst_fpu); fpregs_unlock(); + /* + * Children never inherit PASID state. + * Force it to have its init value: + */ + if (use_xsave()) + dst_fpu->fpstate->regs.xsave.header.xfeatures &= ~XFEATURE_MASK_PASID; + trace_x86_fpu_copy_src(src_fpu); trace_x86_fpu_copy_dst(dst_fpu); -- 2.35.1 _______________________________________________ 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>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "Andy Lutomirski" <luto@kernel.org>, "Tony Luck" <tony.luck@intel.com>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Joerg Roedel" <joro@8bytes.org>, Josh Poimboeuf <jpoimboe@redhat.com>, "Jacob Pan" <jacob.jun.pan@linux.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 v4 06/11] x86/fpu: Clear PASID when copying fpstate Date: Mon, 7 Feb 2022 15:02:49 -0800 [thread overview] Message-ID: <20220207230254.3342514-7-fenghua.yu@intel.com> (raw) In-Reply-To: <20220207230254.3342514-1-fenghua.yu@intel.com> The kernel must allocate a Process Address Space ID (PASID) on behalf of each process which will use ENQCMD and program it into the new MSR to communicate the process identity to platform hardware. ENQCMD uses the PASID stored in this MSR to tag requests from this process. The PASID state must be cleared on fork() since fork creates a new address space. For clone(), it would be functionally OK to copy the PASID. However, clearing it is _also_ functionally OK since any PASID use will trigger the #GP handler to populate the MSR. Copying the PASID state has two main downsides: * It requires differentiating fork() and clone() in the code, both in the FPU code and keeping tsk->pasid_activated consistent. * It guarantees that the PASID is out of its init state, which incurs small but non-zero cost on every XSAVE/XRSTOR. The main downside of clearing the PASID at fpstate copy is the future, one-time #GP for the thread. Use the simplest approach: clear the PASID state both on clone() and fork(). Rely on the #GP handler for MSR population in children. Also, just clear the PASID bit from xfeatures if XSAVE is supported. This will have no effect on systems that do not have PASID support. It is virtually zero overhead because 'dst_fpu' was just written and the whole thing is cache hot. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- v4: - Add "Reviewed-by: Thomas Gleixner <tglx@linutronix.de>" (Thomas). v2: - Rewrite changelog (Dave Hansen). - Move xfeature tweaking into fpu_clone() and make it unconditional if XSAVE is supported (Dave Hansen). arch/x86/kernel/fpu/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 8dea01ffc5c1..19821f027cb3 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -612,6 +612,13 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags) fpu_inherit_perms(dst_fpu); fpregs_unlock(); + /* + * Children never inherit PASID state. + * Force it to have its init value: + */ + if (use_xsave()) + dst_fpu->fpstate->regs.xsave.header.xfeatures &= ~XFEATURE_MASK_PASID; + trace_x86_fpu_copy_src(src_fpu); trace_x86_fpu_copy_dst(dst_fpu); -- 2.35.1
next prev parent reply other threads:[~2022-02-07 23:03 UTC|newest] Thread overview: 214+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-07 23:02 [PATCH v4 00/11] Re-enable ENQCMD and PASID MSR Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 01/11] iommu/sva: Rename CONFIG_IOMMU_SVA_LIB to CONFIG_IOMMU_SVA Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-08 2:39 ` Lu Baolu 2022-02-08 2:39 ` Lu Baolu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 02/11] mm: Change CONFIG option for mm->pasid field Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-08 2:40 ` Lu Baolu 2022-02-08 2:40 ` Lu Baolu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 03/11] iommu/ioasid: Introduce a helper to check for valid PASIDs Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-08 2:40 ` Lu Baolu 2022-02-08 2:40 ` Lu Baolu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 04/11] kernel/fork: Initialize mm's PASID Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-14 17:23 ` Thomas Gleixner 2022-02-14 17:23 ` Thomas Gleixner 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-08 2:41 ` Lu Baolu 2022-02-08 2:41 ` Lu Baolu 2022-02-08 15:01 ` Fenghua Yu 2022-02-08 15:01 ` Fenghua Yu 2022-02-10 3:16 ` Jacob Pan 2022-02-10 3:16 ` Jacob Pan 2022-02-10 16:27 ` Fenghua Yu 2022-02-10 16:27 ` Fenghua Yu 2022-02-10 17:24 ` Luck, Tony 2022-02-10 17:24 ` Luck, Tony 2022-02-10 18:31 ` Fenghua Yu 2022-02-10 18:31 ` Fenghua Yu 2022-02-10 23:52 ` Fenghua Yu 2022-02-10 23:52 ` Fenghua Yu 2022-02-10 18:49 ` Jacob Pan 2022-02-10 18:49 ` Jacob Pan 2022-02-10 23:15 ` Fenghua Yu 2022-02-10 23:15 ` Fenghua Yu 2022-02-11 22:00 ` Dave Hansen 2022-02-11 22:00 ` Dave Hansen 2022-02-14 17:24 ` Thomas Gleixner 2022-02-14 17:24 ` Thomas Gleixner 2022-02-15 9:55 ` Joerg Roedel 2022-02-15 9:55 ` Joerg Roedel 2022-04-11 14:00 ` Zhangfei Gao 2022-04-11 14:10 ` Dave Hansen 2022-04-11 14:10 ` Dave Hansen 2022-04-11 14:20 ` zhangfei.gao 2022-04-11 14:20 ` zhangfei.gao 2022-04-11 14:36 ` Dave Hansen 2022-04-11 14:36 ` Dave Hansen 2022-04-11 14:44 ` zhangfei.gao 2022-04-11 14:44 ` zhangfei.gao 2022-04-11 14:52 ` Dave Hansen 2022-04-11 14:52 ` Dave Hansen 2022-04-11 15:13 ` zhangfei.gao 2022-04-11 15:13 ` zhangfei.gao 2022-04-12 7:04 ` zhangfei.gao 2022-04-12 7:04 ` zhangfei.gao 2022-04-12 13:41 ` Fenghua Yu 2022-04-12 13:41 ` Fenghua Yu 2022-04-12 14:39 ` Dave Hansen 2022-04-12 14:39 ` Dave Hansen 2022-04-15 9:59 ` Fenghua Yu 2022-04-15 9:59 ` Fenghua Yu 2022-04-12 15:35 ` zhangfei.gao 2022-04-12 15:35 ` zhangfei.gao 2022-04-14 10:08 ` zhangfei.gao 2022-04-14 10:08 ` zhangfei.gao 2022-04-15 9:51 ` Fenghua Yu 2022-04-15 9:51 ` Fenghua Yu 2022-04-15 10:14 ` zhangfei.gao 2022-04-15 10:14 ` zhangfei.gao 2022-04-15 10:14 ` zhangfei.gao 2022-04-15 10:50 ` Fenghua Yu 2022-04-15 10:50 ` Fenghua Yu 2022-04-15 11:52 ` zhangfei.gao 2022-04-15 11:52 ` zhangfei.gao 2022-04-15 12:37 ` Fenghua Yu 2022-04-15 12:37 ` Fenghua Yu 2022-04-16 1:30 ` zhangfei.gao 2022-04-16 1:30 ` zhangfei.gao 2022-04-15 19:07 ` Fenghua Yu 2022-04-15 19:07 ` Fenghua Yu 2022-04-15 21:00 ` Jacob Pan 2022-04-15 21:00 ` Jacob Pan 2022-04-16 1:43 ` zhangfei.gao 2022-04-16 1:43 ` zhangfei.gao 2022-04-18 18:14 ` Jacob Pan 2022-04-18 18:14 ` Jacob Pan 2022-04-19 1:02 ` zhangfei.gao 2022-04-19 1:02 ` zhangfei.gao 2022-04-18 6:34 ` Tian, Kevin 2022-04-18 6:34 ` Tian, Kevin 2022-04-18 18:11 ` Jacob Pan 2022-04-18 18:11 ` Jacob Pan 2022-04-20 16:45 ` Jean-Philippe Brucker 2022-04-20 16:45 ` Jean-Philippe Brucker 2022-04-21 6:47 ` zhangfei.gao 2022-04-21 6:47 ` zhangfei.gao 2022-04-22 9:03 ` zhangfei.gao 2022-04-22 9:03 ` zhangfei.gao 2022-04-22 10:11 ` Jean-Philippe Brucker 2022-04-22 10:11 ` Jean-Philippe Brucker 2022-04-22 13:15 ` zhangfei.gao 2022-04-22 13:15 ` zhangfei.gao 2022-04-22 15:50 ` Jean-Philippe Brucker 2022-04-22 15:50 ` Jean-Philippe Brucker 2022-04-23 11:13 ` zhangfei.gao 2022-04-23 11:13 ` zhangfei.gao 2022-04-24 2:58 ` Zhangfei Gao 2022-04-24 2:58 ` Zhangfei Gao 2022-04-24 9:52 ` Zhangfei Gao 2022-04-24 9:52 ` Zhangfei Gao 2022-04-25 13:53 ` Jean-Philippe Brucker 2022-04-25 13:53 ` Jean-Philippe Brucker 2022-04-25 14:18 ` Dave Hansen 2022-04-25 14:18 ` Dave Hansen 2022-04-25 14:26 ` Jean-Philippe Brucker 2022-04-25 14:26 ` Jean-Philippe Brucker 2022-04-25 15:34 ` Jacob Pan 2022-04-25 15:34 ` Jacob Pan 2022-04-25 16:13 ` Jean-Philippe Brucker 2022-04-25 16:13 ` Jean-Philippe Brucker 2022-04-25 22:32 ` Jacob Pan 2022-04-25 22:32 ` Jacob Pan 2022-04-26 4:20 ` Fenghua Yu 2022-04-26 4:20 ` Fenghua Yu 2022-04-26 5:04 ` Zhangfei Gao 2022-04-26 5:04 ` Zhangfei Gao 2022-04-28 0:54 ` Fenghua Yu 2022-04-28 0:54 ` Fenghua Yu 2022-04-28 8:43 ` Jean-Philippe Brucker 2022-04-28 8:43 ` Jean-Philippe Brucker 2022-04-28 15:09 ` Dave Hansen 2022-04-28 15:09 ` Dave Hansen 2022-04-28 15:28 ` Fenghua Yu 2022-04-28 15:28 ` Fenghua Yu 2022-04-28 15:42 ` Dave Hansen 2022-04-28 15:42 ` Dave Hansen 2022-04-28 16:01 ` Jean-Philippe Brucker 2022-04-28 16:01 ` Jean-Philippe Brucker 2022-04-28 16:35 ` Dave Hansen 2022-04-28 16:35 ` Dave Hansen 2022-04-26 4:28 ` Zhangfei Gao 2022-04-26 4:28 ` Zhangfei Gao 2022-04-26 4:36 ` Fenghua Yu 2022-04-26 4:36 ` Fenghua Yu 2022-04-26 5:19 ` Zhangfei Gao 2022-04-26 5:19 ` Zhangfei Gao 2022-04-25 15:55 ` Dave Hansen 2022-04-25 15:55 ` Dave Hansen 2022-04-25 16:40 ` Jean-Philippe Brucker 2022-04-25 16:40 ` Jean-Philippe Brucker 2022-04-26 15:27 ` Dave Hansen 2022-04-26 15:27 ` Dave Hansen 2022-04-26 16:48 ` Jean-Philippe Brucker 2022-04-26 16:48 ` Jean-Philippe Brucker 2022-04-26 23:31 ` Dave Hansen 2022-04-26 23:31 ` Dave Hansen 2022-04-28 8:39 ` Jean-Philippe Brucker 2022-04-28 8:39 ` Jean-Philippe Brucker 2022-04-29 7:53 ` Baolu Lu 2022-04-29 7:53 ` Baolu Lu 2022-04-29 13:51 ` Fenghua Yu 2022-04-29 13:51 ` Fenghua Yu 2022-04-29 14:34 ` Jean-Philippe Brucker 2022-04-29 14:34 ` Jean-Philippe Brucker 2022-04-29 22:19 ` Fenghua Yu 2022-04-29 22:19 ` Fenghua Yu 2022-04-30 7:33 ` Baolu Lu 2022-04-30 7:33 ` Baolu Lu 2022-05-03 7:49 ` Jean-Philippe Brucker 2022-05-03 7:49 ` Jean-Philippe Brucker 2022-05-06 5:36 ` Baolu Lu 2022-05-06 5:36 ` Baolu Lu 2022-04-12 14:36 ` Dave Hansen 2022-04-12 14:36 ` Dave Hansen 2022-04-12 15:10 ` Jean-Philippe Brucker 2022-04-12 15:10 ` Jean-Philippe Brucker 2022-04-12 15:35 ` Dave Hansen 2022-04-12 15:35 ` Dave Hansen 2022-04-13 11:14 ` Lu Baolu 2022-04-13 11:14 ` Lu Baolu 2022-04-25 2:57 ` zhangfei.gao 2022-04-25 2:57 ` zhangfei.gao 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu [this message] 2022-02-07 23:02 ` [PATCH v4 06/11] x86/fpu: Clear PASID when copying fpstate Fenghua Yu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 07/11] sched: Define and initialize a flag to identify valid PASID in the task Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Peter Zijlstra 2022-02-07 23:02 ` [PATCH v4 08/11] x86/traps: Demand-populate PASID MSR via #GP Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 09/11] x86/cpufeatures: Re-enable ENQCMD Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 10/11] tools/objtool: Check for use of the ENQCMD instruction in the kernel Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-15 10:54 ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu 2022-03-09 7:55 ` [tip: x86/core] " tip-bot2 for Fenghua Yu 2022-03-15 10:44 ` tip-bot2 for Fenghua Yu 2022-02-07 23:02 ` [PATCH v4 11/11] docs: x86: Change documentation for SVA (Shared Virtual Addressing) Fenghua Yu 2022-02-07 23:02 ` Fenghua Yu 2022-02-14 17:25 ` Thomas Gleixner 2022-02-14 17:25 ` Thomas Gleixner 2022-02-15 10:54 ` [tip: x86/pasid] Documentation/x86: Update " tip-bot2 for Fenghua Yu 2022-02-11 20:04 ` [PATCH v4 00/11] Re-enable ENQCMD and PASID MSR Fenghua Yu 2022-02-11 20:04 ` Fenghua Yu
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220207230254.3342514-7-fenghua.yu@intel.com \ --to=fenghua.yu@intel.com \ --cc=ashok.raj@intel.com \ --cc=baolu.lu@linux.intel.com \ --cc=bp@alien8.de \ --cc=dave.hansen@linux.intel.com \ --cc=iommu@lists.linux-foundation.org \ --cc=jacob.jun.pan@linux.intel.com \ --cc=joro@8bytes.org \ --cc=jpoimboe@redhat.com \ --cc=linux-kernel@vger.kernel.org \ --cc=luto@kernel.org \ --cc=mingo@redhat.com \ --cc=peterz@infradead.org \ --cc=ravi.v.shankar@intel.com \ --cc=tglx@linutronix.de \ --cc=tony.luck@intel.com \ --cc=x86@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.