From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Joerg Roedel" <joro@8bytes.org>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "H Peter Anvin" <hpa@zytor.com>, "David Woodhouse" <dwmw2@infradead.org>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Dave Hansen" <dave.hansen@intel.com>, "Tony Luck" <tony.luck@intel.com>, "Jean-Philippe Brucker" <jean-philippe@linaro.org>, "Christoph Hellwig" <hch@infradeed.org>, "Ashok Raj" <ashok.raj@intel.com>, "Jacob Jun Pan" <jacob.jun.pan@intel.com>, "Dave Jiang" <dave.jiang@intel.com>, "Sohil Mehta" <sohil.mehta@intel.com>, "Ravi V Shankar" <ravi.v.shankar@intel.com> Cc: "linux-kernel" <linux-kernel@vger.kernel.org>, "x86" <x86@kernel.org>, iommu@lists.linux-foundation.org, Fenghua Yu <fenghua.yu@intel.com> Subject: [PATCH v4 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Date: Thu, 25 Jun 2020 13:17:19 -0700 [thread overview] Message-ID: <1593116242-31507-10-git-send-email-fenghua.yu@intel.com> (raw) In-Reply-To: <1593116242-31507-1-git-send-email-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. 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. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- v2: - Modify init_task_pasid(). arch/x86/kernel/process.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0d5ac0..1b1492e337a6 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -121,6 +121,21 @@ static int set_new_tls(struct task_struct *p, unsigned long tls) return do_set_thread_area_64(p, ARCH_SET_FS, tls); } +/* Initialize the PASID state for the forked/cloned thread. */ +static void init_task_pasid(struct task_struct *task) +{ + struct ia32_pasid_state *ppasid; + + /* + * Initialize the PASID state so that the PASID MSR will be + * initialized to its initial state (0) by XRSTORS when the task is + * scheduled for the first time. + */ + ppasid = get_xsave_addr(&task->thread.fpu.state.xsave, XFEATURE_PASID); + if (ppasid) + ppasid->pasid = INIT_PASID; +} + int copy_thread_tls(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p, unsigned long tls) { @@ -174,6 +189,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, task_user_gs(p) = get_user_gs(current_pt_regs()); #endif + if (static_cpu_has(X86_FEATURE_ENQCMD)) + init_task_pasid(p); + /* Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) ret = set_new_tls(p, tls); -- 2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Joerg Roedel" <joro@8bytes.org>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Peter Zijlstra" <peterz@infradead.org>, "H Peter Anvin" <hpa@zytor.com>, "David Woodhouse" <dwmw2@infradead.org>, "Lu Baolu" <baolu.lu@linux.intel.com>, "Dave Hansen" <dave.hansen@intel.com>, "Tony Luck" <tony.luck@intel.com>, "Jean-Philippe Brucker" <jean-philippe@linaro.org>, "Christoph Hellwig" <hch@infradeed.org>, "Ashok Raj" <ashok.raj@intel.com>, "Jacob Jun Pan" <jacob.jun.pan@intel.com>, "Dave Jiang" <dave.jiang@intel.com>, "Sohil Mehta" <sohil.mehta@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 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Date: Thu, 25 Jun 2020 13:17:19 -0700 [thread overview] Message-ID: <1593116242-31507-10-git-send-email-fenghua.yu@intel.com> (raw) In-Reply-To: <1593116242-31507-1-git-send-email-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. 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. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- v2: - Modify init_task_pasid(). arch/x86/kernel/process.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0d5ac0..1b1492e337a6 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -121,6 +121,21 @@ static int set_new_tls(struct task_struct *p, unsigned long tls) return do_set_thread_area_64(p, ARCH_SET_FS, tls); } +/* Initialize the PASID state for the forked/cloned thread. */ +static void init_task_pasid(struct task_struct *task) +{ + struct ia32_pasid_state *ppasid; + + /* + * Initialize the PASID state so that the PASID MSR will be + * initialized to its initial state (0) by XRSTORS when the task is + * scheduled for the first time. + */ + ppasid = get_xsave_addr(&task->thread.fpu.state.xsave, XFEATURE_PASID); + if (ppasid) + ppasid->pasid = INIT_PASID; +} + int copy_thread_tls(unsigned long clone_flags, unsigned long sp, unsigned long arg, struct task_struct *p, unsigned long tls) { @@ -174,6 +189,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, task_user_gs(p) = get_user_gs(current_pt_regs()); #endif + if (static_cpu_has(X86_FEATURE_ENQCMD)) + init_task_pasid(p); + /* Set a new TLS for the child thread? */ if (clone_flags & CLONE_SETTLS) ret = set_new_tls(p, tls); -- 2.19.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-06-25 20:19 UTC|newest] Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-25 20:17 [PATCH v4 00/12] x86: tag application address space for devices Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 01/12] iommu: Change type of pasid to u32 Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-26 1:13 ` Lu Baolu 2020-06-26 1:13 ` Lu Baolu 2020-06-25 20:17 ` [PATCH v4 02/12] iommu/vt-d: Change flags type to unsigned int in binding mm Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-26 1:14 ` Lu Baolu 2020-06-26 1:14 ` Lu Baolu 2020-06-25 20:17 ` [PATCH v4 03/12] docs: x86: Add documentation for SVA (Shared Virtual Addressing) Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 04/12] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 05/12] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 06/12] x86/msr-index: Define IA32_PASID MSR Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 07/12] mm: Define pasid in mm Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 08/12] fork: Clear PASID for new mm Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu [this message] 2020-06-25 20:17 ` [PATCH v4 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 10/12] x86/mmu: Allocate/free PASID Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-26 1:42 ` Lu Baolu 2020-06-26 1:42 ` Lu Baolu 2020-06-25 20:17 ` [PATCH v4 11/12] sched: Define and initialize a flag to identify valid PASID in the task Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-25 20:17 ` [PATCH v4 12/12] x86/traps: Fix up invalid PASID Fenghua Yu 2020-06-25 20:17 ` Fenghua Yu 2020-06-26 1:46 ` Lu Baolu 2020-06-26 1:46 ` Lu Baolu 2020-06-26 9:44 ` Peter Zijlstra 2020-06-26 9:44 ` Peter Zijlstra 2020-06-26 18:10 ` Luck, Tony 2020-06-26 18:10 ` Luck, Tony 2020-06-26 18:15 ` Borislav Petkov 2020-06-26 18:15 ` Borislav Petkov 2020-06-26 18:23 ` Dave Hansen 2020-06-26 18:23 ` Dave Hansen 2020-06-26 18:35 ` Fenghua Yu 2020-06-26 18:35 ` Fenghua Yu 2020-06-26 18:16 ` Fenghua Yu 2020-06-26 18:16 ` Fenghua Yu
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