From: Fenghua Yu <fenghua.yu@intel.com> To: "Thomas Gleixner" <tglx@linutronix.de>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "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>, "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 6/7] x86/traps: Fix up invalid PASID Date: Mon, 30 Mar 2020 12:33:07 -0700 [thread overview] Message-ID: <1585596788-193989-7-git-send-email-fenghua.yu@intel.com> (raw) In-Reply-To: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> A #GP fault is generated when ENQCMD instruction is executed without a valid PASID value programmed in. The #GP fault handler will initialize the current thread's PASID MSR. The following heuristic is used to avoid decoding the user instructions to determine the precise reason for the #GP fault: 1) If the mm for the process has not been allocated a PASID, this #GP cannot be fixed. 2) If the PASID MSR is already initialized, then the #GP was for some other reason 3) Try initializing the PASID MSR and returning. If the #GP was from an ENQCMD this will fix it. If not, the #GP fault will be repeated and we will hit case "2". Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- arch/x86/include/asm/iommu.h | 1 + arch/x86/kernel/traps.c | 17 +++++++++++++++++ drivers/iommu/intel-svm.c | 37 ++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+) diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h index ed41259fe7ac..e9365a5d6f7d 100644 --- a/arch/x86/include/asm/iommu.h +++ b/arch/x86/include/asm/iommu.h @@ -27,5 +27,6 @@ arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr) } void __free_pasid(struct mm_struct *mm); +bool __fixup_pasid_exception(void); #endif /* _ASM_X86_IOMMU_H */ diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6ef00eb6fbb9..369b5ba94635 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -56,6 +56,7 @@ #include <asm/umip.h> #include <asm/insn.h> #include <asm/insn-eval.h> +#include <asm/iommu.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -488,6 +489,16 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, return GP_CANONICAL; } +static bool fixup_pasid_exception(void) +{ + if (!IS_ENABLED(CONFIG_INTEL_IOMMU_SVM)) + return false; + if (!static_cpu_has(X86_FEATURE_ENQCMD)) + return false; + + return __fixup_pasid_exception(); +} + #define GPFSTR "general protection fault" dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) @@ -499,6 +510,12 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) int ret; RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); + + if (user_mode(regs) && fixup_pasid_exception()) { + cond_local_irq_enable(regs); + return; + } + cond_local_irq_enable(regs); if (static_cpu_has(X86_FEATURE_UMIP)) { diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c index da718a49e91e..5ed39a022adb 100644 --- a/drivers/iommu/intel-svm.c +++ b/drivers/iommu/intel-svm.c @@ -759,3 +759,40 @@ void __free_pasid(struct mm_struct *mm) */ ioasid_free(pasid); } + +/* + * Fix up the PASID MSR if possible. + * + * But if the #GP was due to another reason, a second #GP might be triggered + * to force proper behavior. + */ +bool __fixup_pasid_exception(void) +{ + struct mm_struct *mm; + bool ret = true; + u64 pasid_msr; + int pasid; + + mm = get_task_mm(current); + /* This #GP was triggered from user mode. So mm cannot be NULL. */ + pasid = mm->context.pasid; + /* Ensure this process has been bound to a PASID. */ + if (!pasid) { + ret = false; + goto out; + } + + /* Check to see if the PASID MSR has already been set for this task. */ + rdmsrl(MSR_IA32_PASID, pasid_msr); + if (pasid_msr & MSR_IA32_PASID_VALID) { + ret = false; + goto out; + } + + /* Fix up the MSR. */ + wrmsrl(MSR_IA32_PASID, pasid | MSR_IA32_PASID_VALID); +out: + mmput(mm); + + return ret; +} -- 2.19.1
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>, "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>, "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 6/7] x86/traps: Fix up invalid PASID Date: Mon, 30 Mar 2020 12:33:07 -0700 [thread overview] Message-ID: <1585596788-193989-7-git-send-email-fenghua.yu@intel.com> (raw) In-Reply-To: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> A #GP fault is generated when ENQCMD instruction is executed without a valid PASID value programmed in. The #GP fault handler will initialize the current thread's PASID MSR. The following heuristic is used to avoid decoding the user instructions to determine the precise reason for the #GP fault: 1) If the mm for the process has not been allocated a PASID, this #GP cannot be fixed. 2) If the PASID MSR is already initialized, then the #GP was for some other reason 3) Try initializing the PASID MSR and returning. If the #GP was from an ENQCMD this will fix it. If not, the #GP fault will be repeated and we will hit case "2". Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- arch/x86/include/asm/iommu.h | 1 + arch/x86/kernel/traps.c | 17 +++++++++++++++++ drivers/iommu/intel-svm.c | 37 ++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+) diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h index ed41259fe7ac..e9365a5d6f7d 100644 --- a/arch/x86/include/asm/iommu.h +++ b/arch/x86/include/asm/iommu.h @@ -27,5 +27,6 @@ arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr) } void __free_pasid(struct mm_struct *mm); +bool __fixup_pasid_exception(void); #endif /* _ASM_X86_IOMMU_H */ diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6ef00eb6fbb9..369b5ba94635 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -56,6 +56,7 @@ #include <asm/umip.h> #include <asm/insn.h> #include <asm/insn-eval.h> +#include <asm/iommu.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -488,6 +489,16 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, return GP_CANONICAL; } +static bool fixup_pasid_exception(void) +{ + if (!IS_ENABLED(CONFIG_INTEL_IOMMU_SVM)) + return false; + if (!static_cpu_has(X86_FEATURE_ENQCMD)) + return false; + + return __fixup_pasid_exception(); +} + #define GPFSTR "general protection fault" dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) @@ -499,6 +510,12 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) int ret; RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); + + if (user_mode(regs) && fixup_pasid_exception()) { + cond_local_irq_enable(regs); + return; + } + cond_local_irq_enable(regs); if (static_cpu_has(X86_FEATURE_UMIP)) { diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c index da718a49e91e..5ed39a022adb 100644 --- a/drivers/iommu/intel-svm.c +++ b/drivers/iommu/intel-svm.c @@ -759,3 +759,40 @@ void __free_pasid(struct mm_struct *mm) */ ioasid_free(pasid); } + +/* + * Fix up the PASID MSR if possible. + * + * But if the #GP was due to another reason, a second #GP might be triggered + * to force proper behavior. + */ +bool __fixup_pasid_exception(void) +{ + struct mm_struct *mm; + bool ret = true; + u64 pasid_msr; + int pasid; + + mm = get_task_mm(current); + /* This #GP was triggered from user mode. So mm cannot be NULL. */ + pasid = mm->context.pasid; + /* Ensure this process has been bound to a PASID. */ + if (!pasid) { + ret = false; + goto out; + } + + /* Check to see if the PASID MSR has already been set for this task. */ + rdmsrl(MSR_IA32_PASID, pasid_msr); + if (pasid_msr & MSR_IA32_PASID_VALID) { + ret = false; + goto out; + } + + /* Fix up the MSR. */ + wrmsrl(MSR_IA32_PASID, pasid | MSR_IA32_PASID_VALID); +out: + mmput(mm); + + return ret; +} -- 2.19.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-03-30 20:38 UTC|newest] Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-30 19:33 [PATCH 0/7] x86: tag application address space for devices Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-03-30 19:33 ` [PATCH 1/7] docs: x86: Add a documentation for ENQCMD Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-26 11:02 ` Thomas Gleixner 2020-04-26 11:02 ` Thomas Gleixner 2020-04-27 20:13 ` Fenghua Yu 2020-04-27 20:13 ` Fenghua Yu 2020-03-30 19:33 ` [PATCH 2/7] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-26 11:06 ` Thomas Gleixner 2020-04-26 11:06 ` Thomas Gleixner 2020-04-27 20:17 ` Fenghua Yu 2020-04-27 20:17 ` Fenghua Yu 2020-03-30 19:33 ` [PATCH 3/7] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-26 11:17 ` Thomas Gleixner 2020-04-26 11:17 ` Thomas Gleixner 2020-04-27 20:33 ` Fenghua Yu 2020-04-27 20:33 ` Fenghua Yu 2020-03-30 19:33 ` [PATCH 4/7] x86/msr-index: Define IA32_PASID MSR Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-26 11:22 ` Thomas Gleixner 2020-04-26 11:22 ` Thomas Gleixner 2020-04-27 20:50 ` Fenghua Yu 2020-04-27 20:50 ` Fenghua Yu 2020-03-30 19:33 ` [PATCH 5/7] x86/mmu: Allocate/free PASID Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-26 14:55 ` Thomas Gleixner 2020-04-26 14:55 ` Thomas Gleixner 2020-04-27 22:18 ` Fenghua Yu 2020-04-27 22:18 ` Fenghua Yu 2020-04-27 23:44 ` Thomas Gleixner 2020-04-27 23:44 ` Thomas Gleixner 2020-04-28 18:21 ` Jacob Pan (Jun) 2020-04-28 18:21 ` Jacob Pan (Jun) 2020-04-28 18:54 ` Thomas Gleixner 2020-04-28 18:54 ` Thomas Gleixner 2020-04-28 19:07 ` Luck, Tony 2020-04-28 19:07 ` Luck, Tony 2020-04-28 20:42 ` Jacob Pan (Jun) 2020-04-28 20:42 ` Jacob Pan (Jun) 2020-04-28 20:59 ` Luck, Tony 2020-04-28 20:59 ` Luck, Tony 2020-04-28 22:13 ` Jacob Pan (Jun) 2020-04-28 22:13 ` Jacob Pan (Jun) 2020-04-28 22:32 ` Luck, Tony 2020-04-28 22:32 ` Luck, Tony 2020-04-28 20:40 ` Jacob Pan (Jun) 2020-04-28 20:40 ` Jacob Pan (Jun) 2020-04-28 20:57 ` Fenghua Yu 2020-04-28 20:57 ` Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu [this message] 2020-03-30 19:33 ` [PATCH 6/7] x86/traps: Fix up invalid PASID Fenghua Yu 2020-04-26 15:25 ` Thomas Gleixner 2020-04-26 15:25 ` Thomas Gleixner 2020-04-27 20:11 ` Fenghua Yu 2020-04-27 20:11 ` Fenghua Yu 2020-04-28 0:13 ` Thomas Gleixner 2020-04-28 0:13 ` Thomas Gleixner 2020-04-27 22:46 ` Raj, Ashok 2020-04-27 22:46 ` Raj, Ashok 2020-04-27 23:08 ` Luck, Tony 2020-04-27 23:08 ` Luck, Tony 2020-04-28 0:20 ` Thomas Gleixner 2020-04-28 0:20 ` Thomas Gleixner 2020-04-28 0:54 ` Thomas Gleixner 2020-04-28 0:54 ` Thomas Gleixner 2020-04-28 1:08 ` Raj, Ashok 2020-04-28 1:08 ` Raj, Ashok 2020-03-30 19:33 ` [PATCH 7/7] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu 2020-03-30 19:33 ` Fenghua Yu 2020-04-22 20:41 ` [PATCH 0/7] x86: tag application address space for devices Fenghua Yu 2020-04-22 20:41 ` Fenghua Yu
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