Hi Janis,
Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx> writes:
> KVM needs a mechanism to do accesses to guest memory that honor
> storage key protection.
> Since the copy_to/from_user implementation makes use of move
> instructions that support having an additional access key supplied,
> we can implement __copy_from/to_user_with_key by enhancing the
> existing implementation.
>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
This doesn't apply to my master branch.
> diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
> index d3a700385875..ce7a150dd93a 100644
> --- a/arch/s390/lib/uaccess.c
> +++ b/arch/s390/lib/uaccess.c
> @@ -59,11 +59,13 @@ static inline int copy_with_mvcos(void)
> #endif
>
> static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
> - unsigned long size)
> + unsigned long size, char key)
> {
> unsigned long tmp1, tmp2;
> union oac spec = {
> + .oac2.key = key,
> .oac2.as = PSW_BITS_AS_SECONDARY,
> + .oac2.k = 1,
> .oac2.a = 1,
> };
>
> @@ -94,19 +96,19 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr
> }
>
> static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
> - unsigned long size)
> + unsigned long size, char key)
Any special reason for using 'char' as type for key here? Given the left shift
below i would prefer 'unsigned char' to avoid having to think about
whether this can overflow. The end result wouldn't look different,
so more or less a cosmetic issue.
> {
> unsigned long tmp1, tmp2;
>
> tmp1 = -256UL;
> asm volatile(
> " sacf 0\n"
> - "0: mvcp 0(%0,%2),0(%1),%3\n"
> + "0: mvcp 0(%0,%2),0(%1),%[key]\n"
> "7: jz 5f\n"
> "1: algr %0,%3\n"
> " la %1,256(%1)\n"
> " la %2,256(%2)\n"
> - "2: mvcp 0(%0,%2),0(%1),%3\n"
> + "2: mvcp 0(%0,%2),0(%1),%[key]\n"
> "8: jnz 1b\n"
> " j 5f\n"
> "3: la %4,255(%1)\n" /* %4 = ptr + 255 */
> @@ -115,7 +117,7 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
> " slgr %4,%1\n"
> " clgr %0,%4\n" /* copy crosses next page boundary? */
> " jnh 6f\n"
> - "4: mvcp 0(%4,%2),0(%1),%3\n"
> + "4: mvcp 0(%4,%2),0(%1),%[key]\n"
> "9: slgr %0,%4\n"
> " j 6f\n"
> "5: slgr %0,%0\n"
> @@ -123,24 +125,36 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
> EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
> EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
> : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
> - : : "cc", "memory");
> + : [key] "d" (key << 4)
> + : "cc", "memory");
> return size;
> }
>
With that minor nitpick:
Reviewed-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
