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Merge tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 PASID support from Thomas Gleixner:
 "Reenable ENQCMD/PASID support:

   - Simplify the PASID handling to allocate the PASID once, associate
     it to the mm of a process and free it on mm_exit().

     The previous attempt of refcounted PASIDs and dynamic
     alloc()/free() turned out to be error prone and too complex. The
     PASID space is 20bits, so the case of resource exhaustion is a pure
     academic concern.

   - Populate the PASID MSR on demand via #GP to avoid racy updates via
     IPIs.

   - Reenable ENQCMD and let objtool check for the forbidden usage of
     ENQCMD in the kernel.

   - Update the documentation for Shared Virtual Addressing accordingly"

* tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation/x86: Update documentation for SVA (Shared Virtual Addressing)
  tools/objtool: Check for use of the ENQCMD instruction in the kernel
  x86/cpufeatures: Re-enable ENQCMD
  x86/traps: Demand-populate PASID MSR via #GP
  sched: Define and initialize a flag to identify valid PASID in the task
  x86/fpu: Clear PASID when copying fpstate
  iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
  kernel/fork: Initialize mm's PASID
  iommu/ioasid: Introduce a helper to check for valid PASIDs
  mm: Change CONFIG option for mm->pasid field
  iommu/sva: Rename CONFIG_IOMMU_SVA_LIB to CONFIG_IOMMU_SVA
This commit is contained in:
Linus Torvalds
2022-03-21 12:28:13 -07:00
parent eaa54b1458 83aa52ffed
commit 3fd33273a4
20 changed files with 195 additions and 118 deletions
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15
kernel/fork.c
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@@ -97,6 +97,7 @@
#include <linux/scs.h>
#include <linux/io_uring.h>
#include <linux/bpf.h>
#include <linux/sched/mm.h>
#include <asm/pgalloc.h>
#include <linux/uaccess.h>
@@ -967,6 +968,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
tsk->use_memdelay = 0;
#endif
#ifdef CONFIG_IOMMU_SVA
tsk->pasid_activated = 0;
#endif
#ifdef CONFIG_MEMCG
tsk->active_memcg = NULL;
#endif
@@ -1019,13 +1024,6 @@ static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
#endif
}
static void mm_init_pasid(struct mm_struct *mm)
{
#ifdef CONFIG_IOMMU_SUPPORT
mm->pasid = INIT_PASID;
#endif
}
static void mm_init_uprobes_state(struct mm_struct *mm)
{
#ifdef CONFIG_UPROBES
@@ -1054,7 +1052,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm_init_cpumask(mm);
mm_init_aio(mm);
mm_init_owner(mm, p);
mm_init_pasid(mm);
mm_pasid_init(mm);
RCU_INIT_POINTER(mm->exe_file, NULL);
mmu_notifier_subscriptions_init(mm);
init_tlb_flush_pending(mm);
@@ -1121,6 +1119,7 @@ static inline void __mmput(struct mm_struct *mm)
}
if (mm->binfmt)
module_put(mm->binfmt->module);
mm_pasid_drop(mm);
mmdrop(mm);
}