s390/kvm,gaccess: shorten copy_to/from_guest code

The code can be significantly shortened. There is no functional change,
except that for large (> PAGE_SIZE) copies the guest translation would
be done more frequently.
However, there is not a single user which does this currently. If one
gets added later on this functionality can be added easily again.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index 82f450e..8608d7e 100644 (file)
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -18,16 +18,19 @@
 #include <asm/uaccess.h>
 #include "kvm-s390.h"
 
-static inline void *__gptr_to_uptr(struct kvm_vcpu *vcpu, void *gptr)
+static inline void *__gptr_to_uptr(struct kvm_vcpu *vcpu, void *gptr,
+                                  int prefixing)
 {
        unsigned long prefix  = vcpu->arch.sie_block->prefix;
        unsigned long gaddr = (unsigned long) gptr;
        unsigned long uaddr;
 
-       if (gaddr < 2 * PAGE_SIZE)
-               gaddr += prefix;
-       else if ((gaddr >= prefix) && (gaddr < prefix + 2 * PAGE_SIZE))
-               gaddr -= prefix;
+       if (prefixing) {
+               if (gaddr < 2 * PAGE_SIZE)
+                       gaddr += prefix;
+               else if ((gaddr >= prefix) && (gaddr < prefix + 2 * PAGE_SIZE))
+                       gaddr -= prefix;
+       }
        uaddr = gmap_fault(gaddr, vcpu->arch.gmap);
        if (IS_ERR_VALUE(uaddr))
                uaddr = -EFAULT;
@@ -36,7 +39,7 @@ static inline void *__gptr_to_uptr(struct kvm_vcpu *vcpu, void *gptr)
 
 #define get_guest(vcpu, x, gptr)                               \
 ({                                                             \
-       __typeof__(gptr) __uptr = __gptr_to_uptr(vcpu, gptr);   \
+       __typeof__(gptr) __uptr = __gptr_to_uptr(vcpu, gptr, 1);\
        int __mask = sizeof(__typeof__(*(gptr))) - 1;           \
        int __ret = PTR_RET(__uptr);                            \
                                                                \
@@ -49,7 +52,7 @@ static inline void *__gptr_to_uptr(struct kvm_vcpu *vcpu, void *gptr)
 
 #define put_guest(vcpu, x, gptr)                               \
 ({                                                             \
-       __typeof__(gptr) __uptr = __gptr_to_uptr(vcpu, gptr);   \
+       __typeof__(gptr) __uptr = __gptr_to_uptr(vcpu, gptr, 1);\
        int __mask = sizeof(__typeof__(*(gptr))) - 1;           \
        int __ret = PTR_RET(__uptr);                            \
                                                                \
@@ -60,255 +63,40 @@ static inline void *__gptr_to_uptr(struct kvm_vcpu *vcpu, void *gptr)
        __ret;                                                  \
 })
 
-static inline int __copy_to_guest_slow(struct kvm_vcpu *vcpu,
-                                      unsigned long guestdest,
-                                      void *from, unsigned long n)
-{
-       int rc;
-       unsigned long i;
-       u8 *data = from;
-
-       for (i = 0; i < n; i++) {
-               rc = put_guest(vcpu, *(data++), (u8 *)guestdest++);
-               if (rc < 0)
-                       return rc;
-       }
-       return 0;
-}
-
-static inline int __copy_to_guest_fast(struct kvm_vcpu *vcpu,
-                                      unsigned long guestdest,
-                                      void *from, unsigned long n)
-{
-       int r;
-       void __user *uptr;
-       unsigned long size;
-
-       if (guestdest + n < guestdest)
-               return -EFAULT;
-
-       /* simple case: all within one segment table entry? */
-       if ((guestdest & PMD_MASK) == ((guestdest+n) & PMD_MASK)) {
-               uptr = (void __user *) gmap_fault(guestdest, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
-
-               r = copy_to_user(uptr, from, n);
-
-               if (r)
-                       r = -EFAULT;
-
-               goto out;
-       }
-
-       /* copy first segment */
-       uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
-
-       if (IS_ERR((void __force *) uptr))
-               return PTR_ERR((void __force *) uptr);
-
-       size = PMD_SIZE - (guestdest & ~PMD_MASK);
-
-       r = copy_to_user(uptr, from, size);
-
-       if (r) {
-               r = -EFAULT;
-               goto out;
-       }
-       from += size;
-       n -= size;
-       guestdest += size;
-
-       /* copy full segments */
-       while (n >= PMD_SIZE) {
-               uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
-
-               r = copy_to_user(uptr, from, PMD_SIZE);
-
-               if (r) {
-                       r = -EFAULT;
-                       goto out;
-               }
-               from += PMD_SIZE;
-               n -= PMD_SIZE;
-               guestdest += PMD_SIZE;
-       }
-
-       /* copy the tail segment */
-       if (n) {
-               uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
-
-               r = copy_to_user(uptr, from, n);
-
-               if (r)
-                       r = -EFAULT;
-       }
-out:
-       return r;
-}
-
-static inline int copy_to_guest_absolute(struct kvm_vcpu *vcpu,
-                                        unsigned long guestdest,
-                                        void *from, unsigned long n)
-{
-       return __copy_to_guest_fast(vcpu, guestdest, from, n);
-}
-
-static inline int copy_to_guest(struct kvm_vcpu *vcpu, unsigned long guestdest,
-                               void *from, unsigned long n)
-{
-       unsigned long prefix  = vcpu->arch.sie_block->prefix;
-
-       if ((guestdest < 2 * PAGE_SIZE) && (guestdest + n > 2 * PAGE_SIZE))
-               goto slowpath;
-
-       if ((guestdest < prefix) && (guestdest + n > prefix))
-               goto slowpath;
-
-       if ((guestdest < prefix + 2 * PAGE_SIZE)
-           && (guestdest + n > prefix + 2 * PAGE_SIZE))
-               goto slowpath;
-
-       if (guestdest < 2 * PAGE_SIZE)
-               guestdest += prefix;
-       else if ((guestdest >= prefix) && (guestdest < prefix + 2 * PAGE_SIZE))
-               guestdest -= prefix;
-
-       return __copy_to_guest_fast(vcpu, guestdest, from, n);
-slowpath:
-       return __copy_to_guest_slow(vcpu, guestdest, from, n);
-}
-
-static inline int __copy_from_guest_slow(struct kvm_vcpu *vcpu, void *to,
-                                        unsigned long guestsrc,
-                                        unsigned long n)
+static inline int __copy_guest(struct kvm_vcpu *vcpu, unsigned long to,
+                              unsigned long from, unsigned long len,
+                              int to_guest, int prefixing)
 {
-       int rc;
-       unsigned long i;
-       u8 *data = to;
-
-       for (i = 0; i < n; i++) {
-               rc = get_guest(vcpu, *(data++), (u8 *)guestsrc++);
-               if (rc < 0)
-                       return rc;
+       unsigned long _len, rc;
+       void *uptr;
+
+       while (len) {
+               uptr = to_guest ? (void *)to : (void *)from;
+               uptr = __gptr_to_uptr(vcpu, uptr, prefixing);
+               if (IS_ERR(uptr))
+                       return -EFAULT;
+               _len = PAGE_SIZE - ((unsigned long)uptr & (PAGE_SIZE - 1));
+               _len = min(_len, len);
+               if (to_guest)
+                       rc = copy_to_user(uptr, (void *)from, _len);
+               else
+                       rc = copy_from_user((void *)to, uptr, _len);
+               if (rc)
+                       return -EFAULT;
+               len -= _len;
+               from += _len;
+               to += _len;
        }
        return 0;
 }
 
-static inline int __copy_from_guest_fast(struct kvm_vcpu *vcpu, void *to,
-                                        unsigned long guestsrc,
-                                        unsigned long n)
-{
-       int r;
-       void __user *uptr;
-       unsigned long size;
-
-       if (guestsrc + n < guestsrc)
-               return -EFAULT;
-
-       /* simple case: all within one segment table entry? */
-       if ((guestsrc & PMD_MASK) == ((guestsrc+n) & PMD_MASK)) {
-               uptr = (void __user *) gmap_fault(guestsrc, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
-
-               r = copy_from_user(to, uptr, n);
-
-               if (r)
-                       r = -EFAULT;
-
-               goto out;
-       }
-
-       /* copy first segment */
-       uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
-
-       if (IS_ERR((void __force *) uptr))
-               return PTR_ERR((void __force *) uptr);
-
-       size = PMD_SIZE - (guestsrc & ~PMD_MASK);
-
-       r = copy_from_user(to, uptr, size);
-
-       if (r) {
-               r = -EFAULT;
-               goto out;
-       }
-       to += size;
-       n -= size;
-       guestsrc += size;
-
-       /* copy full segments */
-       while (n >= PMD_SIZE) {
-               uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
+#define copy_to_guest(vcpu, to, from, size) \
+       __copy_guest(vcpu, to, (unsigned long)from, size, 1, 1)
+#define copy_from_guest(vcpu, to, from, size) \
+       __copy_guest(vcpu, (unsigned long)to, from, size, 0, 1)
+#define copy_to_guest_absolute(vcpu, to, from, size) \
+       __copy_guest(vcpu, to, (unsigned long)from, size, 1, 0)
+#define copy_from_guest_absolute(vcpu, to, from, size) \
+       __copy_guest(vcpu, (unsigned long)to, from, size, 0, 0)
 
-               r = copy_from_user(to, uptr, PMD_SIZE);
-
-               if (r) {
-                       r = -EFAULT;
-                       goto out;
-               }
-               to += PMD_SIZE;
-               n -= PMD_SIZE;
-               guestsrc += PMD_SIZE;
-       }
-
-       /* copy the tail segment */
-       if (n) {
-               uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
-
-               if (IS_ERR((void __force *) uptr))
-                       return PTR_ERR((void __force *) uptr);
-
-               r = copy_from_user(to, uptr, n);
-
-               if (r)
-                       r = -EFAULT;
-       }
-out:
-       return r;
-}
-
-static inline int copy_from_guest_absolute(struct kvm_vcpu *vcpu, void *to,
-                                          unsigned long guestsrc,
-                                          unsigned long n)
-{
-       return __copy_from_guest_fast(vcpu, to, guestsrc, n);
-}
-
-static inline int copy_from_guest(struct kvm_vcpu *vcpu, void *to,
-                                 unsigned long guestsrc, unsigned long n)
-{
-       unsigned long prefix  = vcpu->arch.sie_block->prefix;
-
-       if ((guestsrc < 2 * PAGE_SIZE) && (guestsrc + n > 2 * PAGE_SIZE))
-               goto slowpath;
-
-       if ((guestsrc < prefix) && (guestsrc + n > prefix))
-               goto slowpath;
-
-       if ((guestsrc < prefix + 2 * PAGE_SIZE)
-           && (guestsrc + n > prefix + 2 * PAGE_SIZE))
-               goto slowpath;
-
-       if (guestsrc < 2 * PAGE_SIZE)
-               guestsrc += prefix;
-       else if ((guestsrc >= prefix) && (guestsrc < prefix + 2 * PAGE_SIZE))
-               guestsrc -= prefix;
-
-       return __copy_from_guest_fast(vcpu, to, guestsrc, n);
-slowpath:
-       return __copy_from_guest_slow(vcpu, to, guestsrc, n);
-}
-#endif
+#endif /* __KVM_S390_GACCESS_H */