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KVM: PPC: Book3S HV: use get_user()/put_user() for the HPT fd

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kvm_htab_read() and kvm_htab_write() check the user buffer with
access_ok() once and then move each HPT entry with two __put_user() or
__get_user() calls, with real work between entries.  Each of those
accesses opens and closes user access on its own, so the up-front check
saves nothing.

Use put_user() and get_user().  On powerpc the only difference is the
address check: __get_user() and __put_user() already do might_fault().
kvm_htab_write() holds mmu_setup_lock across the loop, but it already
reads each header with __copy_from_user() under that lock, so nothing
new happens under it.  The access_ok() calls stay.

This is part of getting rid of __get_user() and __put_user() entirely.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2026-10-20 10:02:53 -10:00
parent 05b163dab2
commit a79bb50808
1 changed files with 4 additions and 4 deletions
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8
arch/powerpc/kvm/book3s_64_mmu_hv.c
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@ -1749,8 +1749,8 @@ static ssize_t kvm_htab_read(struct file *file, char __user *buf,
record_hpte(flags, hptp, hpte, revp, 1, first_pass)) {
/* valid entry, write it out */
++hdr.n_valid;
if (__put_user(hpte[0], lbuf) ||
__put_user(hpte[1], lbuf + 1))
if (put_user(hpte[0], lbuf) ||
put_user(hpte[1], lbuf + 1))
return -EFAULT;
nb += HPTE_SIZE;
lbuf += 2;
@ -1853,8 +1853,8 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf,
__be64 hpte_r;
err = -EFAULT;
if (__get_user(hpte_v, lbuf) ||
__get_user(hpte_r, lbuf + 1))
if (get_user(hpte_v, lbuf) ||
get_user(hpte_r, lbuf + 1))
goto out;
v = be64_to_cpu(hpte_v);
r = be64_to_cpu(hpte_r);