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>

1 files changed, 41 insertions, 253 deletions

diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index 82f450ecb585..8608d7e6a334 100644
--- 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 */