> +/**
> + * gmap_pmd_op_walk - walk the gmap tables, get the guest table lock
> + * and return the pmd pointer
> + * @gmap: pointer to guest mapping meta data structure
> + * @gaddr: virtual address in the guest address space
> + *
> + * Returns a pointer to the pmd for a guest address, or NULL
> + */
> +static inline pmd_t *gmap_pmd_op_walk(struct gmap *gmap, unsigned long gaddr)
> +{
> + pmd_t *pmdp;
> +
> + BUG_ON(gmap_is_shadow(gmap));
> + spin_lock(&gmap->guest_table_lock);
> + pmdp = (pmd_t *) gmap_table_walk(gmap, gaddr, 1);
> +
So gmap_table_walk() now basically always has to be called with the
guest_table_lock held. We could add a BUG/WARN for that in
gmap_table_walk().
> + if (!pmdp || pmd_none(*pmdp)) {
> + spin_unlock(&gmap->guest_table_lock);
> + return NULL;
> + }
> +
> + /* 4k page table entries are locked via the pte (pte_alloc_map_lock). */
> + if (!pmd_large(*pmdp))
> + spin_unlock(&gmap->guest_table_lock);
> + return pmdp;
> +}
> +
> +/**
> + * gmap_pmd_op_end - release the guest_table_lock if needed
> + * @gmap: pointer to the guest mapping meta data structure
> + * @pmdp: pointer to the pmd
> + */
> +static inline void gmap_pmd_op_end(struct gmap *gmap, pmd_t *pmdp)
> +{
> + if (pmd_large(*pmdp))
> + spin_unlock(&gmap->guest_table_lock);
> +}
> +
> +/*
> + * gmap_protect_pte - remove access rights to memory and set pgste bits
> + * @gmap: pointer to guest mapping meta data structure
> + * @gaddr: virtual address in the guest address space
> + * @pmdp: pointer to the pmd associated with the pte
> + * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
> + * @bits: pgste notification bits to set
> + *
> + * Returns 0 if successfully protected, -ENOMEM if out of memory and
> + * -EAGAIN if a fixup is needed.
> + *
> + * Expected to be called with sg->mm->mmap_sem in read and
> + * guest_table_lock held for shadow gmaps.
> + */
stale comment about shadow gmaps.
> +static int gmap_protect_pte(struct gmap *gmap, unsigned long gaddr,
> + pmd_t *pmdp, int prot, unsigned long bits)
> +{
> + int rc;
> + pte_t *ptep;
> + spinlock_t *ptl = NULL;
> +
> + ptep = pte_alloc_map_lock(gmap->mm, pmdp, gaddr, &ptl);
> + if (!ptep)
> + return -ENOMEM;
> +
> + /* Protect and unlock. */
> + rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, bits);
> + gmap_pte_op_end(ptl);
> + return rc;
> }
>
> /*
> @@ -896,16 +966,20 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
> unsigned long len, int prot, unsigned long bits)
> {
> unsigned long vmaddr;
> - spinlock_t *ptl;
> - pte_t *ptep;
> + pmd_t *pmdp;
> int rc;
>
> while (len) {
> rc = -EAGAIN;
> - ptep = gmap_pte_op_walk(gmap, gaddr, &ptl);
> - if (ptep) {
> - rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, bits);
> - gmap_pte_op_end(ptl);
> + pmdp = gmap_pmd_op_walk(gmap, gaddr);
> + if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
You could move the !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID) check into
either gmap_pmd_op_walk() or gmap_protect_pte(). Makes this easier to
read (and you already have similar checks in gmap_pmd_op_walk() )
> + rc = gmap_protect_pte(gmap, gaddr, pmdp, prot,
> + bits);
> + if (!rc) {
> + len -= PAGE_SIZE;
> + gaddr += PAGE_SIZE;
> + }
> + gmap_pmd_op_end(gmap, pmdp);
> }
> if (rc) {
> vmaddr = __gmap_translate(gmap, gaddr);
> @@ -914,10 +988,7 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
> rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, prot);
> if (rc)
> return rc;
> - continue;
> }
> - gaddr += PAGE_SIZE;
> - len -= PAGE_SIZE;
> }
> return 0;
> }
>
Apart from that, looks good to me.
--
Thanks,
David / dhildenb
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