IOMMU and SVA-capable devices know nothing about LAM and only expect
canonical addresses. An attempt to pass down tagged pointer will lead
to address translation failure.
By default do not allow to enable both LAM and use SVA in the same
process.
The new ARCH_FORCE_TAGGED_SVA arch_prctl() overrides the limitation.
By using the arch_prctl() userspace takes responsibility to never pass
tagged address to the device.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-12-kirill.shutemov%40linux.intel.com
#define MM_CONTEXT_HAS_VSYSCALL 1
/* Do not allow changing LAM mode */
#define MM_CONTEXT_LOCK_LAM 2
+/* Allow LAM and SVA coexisting */
+#define MM_CONTEXT_FORCE_TAGGED_SVA 3
/*
* x86 has arch-specific MMU state beyond what lives in mm_struct.
mm->context.untag_mask = -1UL;
}
+#define arch_pgtable_dma_compat arch_pgtable_dma_compat
+static inline bool arch_pgtable_dma_compat(struct mm_struct *mm)
+{
+ return !mm_lam_cr3_mask(mm) ||
+ test_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &mm->context.flags);
+}
#else
static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm)
#define ARCH_GET_UNTAG_MASK 0x4001
#define ARCH_ENABLE_TAGGED_ADDR 0x4002
#define ARCH_GET_MAX_TAG_BITS 0x4003
+#define ARCH_FORCE_TAGGED_SVA 0x4004
#endif /* _ASM_X86_PRCTL_H */
if (current->mm != mm)
return -EINVAL;
+ if (mm_valid_pasid(mm) &&
+ !test_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &mm->context.flags))
+ return -EINTR;
+
if (mmap_write_lock_killable(mm))
return -EINTR;
(unsigned long __user *)arg2);
case ARCH_ENABLE_TAGGED_ADDR:
return prctl_enable_tagged_addr(task->mm, arg2);
+ case ARCH_FORCE_TAGGED_SVA:
+ set_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &task->mm->context.flags);
+ return 0;
case ARCH_GET_MAX_TAG_BITS:
if (!cpu_feature_enabled(X86_FEATURE_LAM))
return put_user(0, (unsigned long __user *)arg2);
/*
* Helpers for IOMMU drivers implementing SVA
*/
+#include <linux/mmu_context.h>
#include <linux/mutex.h>
#include <linux/sched/mm.h>
#include <linux/iommu.h>
min == 0 || max < min)
return -EINVAL;
+ if (!arch_pgtable_dma_compat(mm))
+ return -EBUSY;
+
mutex_lock(&iommu_sva_lock);
/* Is a PASID already associated with this mm? */
if (mm_valid_pasid(mm)) {
}
#endif
+#ifndef arch_pgtable_dma_compat
+static inline bool arch_pgtable_dma_compat(struct mm_struct *mm)
+{
+ return true;
+}
+#endif
+
#endif