[xen master] x86/HVM: __hvm_copy()'s size parameter is an unsigned quantity

[patchbot@xxxxxxx]

commit d3ff3e48db4a59d1972bcdeb08cac22048d14b27
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Apr 8 13:11:24 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Apr 8 13:11:24 2020 +0200

    x86/HVM: __hvm_copy()'s size parameter is an unsigned quantity
    
    There are no negative sizes. Make the function's parameter as well as
    that of its derivates "unsigned int". Similarly make its local "count"
    variable "unsigned int", and drop "todo" altogether. Don't use min_t()
    anymore to calculate "count". Restrict its scope as well as that of
    other local variables of the function.
    
    While at it I've also noticed that {copy_{from,to},clear}_user_hvm()
    have been returning "unsigned long" for no apparent reason, as their
    respective "size" parameters have already been "unsigned int". Adjust
    this as well as a slightly wrong comment there at the same time.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Paul Durrant <pdurrant@xxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c                 | 34 ++++++++++++++++------------------
 xen/include/asm-x86/hvm/guest_access.h |  6 +++---
 xen/include/asm-x86/hvm/support.h      |  8 ++++----
 3 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 304b3d1562..827c5fa89d 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3227,15 +3227,10 @@ enum hvm_translation_result hvm_translate_get_page(
 #define HVMCOPY_phys       (0u<<2)
 #define HVMCOPY_linear     (1u<<2)
 static enum hvm_translation_result __hvm_copy(
-    void *buf, paddr_t addr, int size, struct vcpu *v, unsigned int flags,
+    void *buf, paddr_t addr, unsigned int size, struct vcpu *v, unsigned int 
flags,
     uint32_t pfec, pagefault_info_t *pfinfo)
 {
-    gfn_t gfn;
-    struct page_info *page;
-    p2m_type_t p2mt;
     char *p;
-    int count, todo = size;
-
     ASSERT(is_hvm_vcpu(v));
 
     /*
@@ -3254,12 +3249,14 @@ static enum hvm_translation_result __hvm_copy(
         return HVMTRANS_unhandleable;
 #endif
 
-    while ( todo > 0 )
+    while ( size > 0 )
     {
+        struct page_info *page;
+        gfn_t gfn;
+        p2m_type_t p2mt;
         enum hvm_translation_result res;
         unsigned int pgoff = addr & ~PAGE_MASK;
-
-        count = min_t(int, PAGE_SIZE - pgoff, todo);
+        unsigned int count = min((unsigned int)PAGE_SIZE - pgoff, size);
 
         res = hvm_translate_get_page(v, addr, flags & HVMCOPY_linear,
                                      pfec, pfinfo, &page, &gfn, &p2mt);
@@ -3313,7 +3310,7 @@ static enum hvm_translation_result __hvm_copy(
         addr += count;
         if ( buf )
             buf += count;
-        todo -= count;
+        size -= count;
         put_page(page);
     }
 
@@ -3321,21 +3318,21 @@ static enum hvm_translation_result __hvm_copy(
 }
 
 enum hvm_translation_result hvm_copy_to_guest_phys(
-    paddr_t paddr, void *buf, int size, struct vcpu *v)
+    paddr_t paddr, void *buf, unsigned int size, struct vcpu *v)
 {
     return __hvm_copy(buf, paddr, size, v,
                       HVMCOPY_to_guest | HVMCOPY_phys, 0, NULL);
 }
 
 enum hvm_translation_result hvm_copy_from_guest_phys(
-    void *buf, paddr_t paddr, int size)
+    void *buf, paddr_t paddr, unsigned int size)
 {
     return __hvm_copy(buf, paddr, size, current,
                       HVMCOPY_from_guest | HVMCOPY_phys, 0, NULL);
 }
 
 enum hvm_translation_result hvm_copy_to_guest_linear(
-    unsigned long addr, void *buf, int size, uint32_t pfec,
+    unsigned long addr, void *buf, unsigned int size, uint32_t pfec,
     pagefault_info_t *pfinfo)
 {
     return __hvm_copy(buf, addr, size, current,
@@ -3344,7 +3341,7 @@ enum hvm_translation_result hvm_copy_to_guest_linear(
 }
 
 enum hvm_translation_result hvm_copy_from_guest_linear(
-    void *buf, unsigned long addr, int size, uint32_t pfec,
+    void *buf, unsigned long addr, unsigned int size, uint32_t pfec,
     pagefault_info_t *pfinfo)
 {
     return __hvm_copy(buf, addr, size, current,
@@ -3352,7 +3349,7 @@ enum hvm_translation_result hvm_copy_from_guest_linear(
                       PFEC_page_present | pfec, pfinfo);
 }
 
-unsigned long copy_to_user_hvm(void *to, const void *from, unsigned int len)
+unsigned int copy_to_user_hvm(void *to, const void *from, unsigned int len)
 {
     int rc;
 
@@ -3366,7 +3363,7 @@ unsigned long copy_to_user_hvm(void *to, const void 
*from, unsigned int len)
     return rc ? len : 0; /* fake a copy_to_user() return code */
 }
 
-unsigned long clear_user_hvm(void *to, unsigned int len)
+unsigned int clear_user_hvm(void *to, unsigned int len)
 {
     int rc;
 
@@ -3377,10 +3374,11 @@ unsigned long clear_user_hvm(void *to, unsigned int len)
     }
 
     rc = hvm_copy_to_guest_linear((unsigned long)to, NULL, len, 0, NULL);
-    return rc ? len : 0; /* fake a copy_to_user() return code */
+
+    return rc ? len : 0; /* fake a clear_user() return code */
 }
 
-unsigned long copy_from_user_hvm(void *to, const void *from, unsigned len)
+unsigned int copy_from_user_hvm(void *to, const void *from, unsigned int len)
 {
     int rc;
 
diff --git a/xen/include/asm-x86/hvm/guest_access.h 
b/xen/include/asm-x86/hvm/guest_access.h
index b92dbe90d5..edacba75db 100644
--- a/xen/include/asm-x86/hvm/guest_access.h
+++ b/xen/include/asm-x86/hvm/guest_access.h
@@ -1,8 +1,8 @@
 #ifndef __ASM_X86_HVM_GUEST_ACCESS_H__
 #define __ASM_X86_HVM_GUEST_ACCESS_H__
 
-unsigned long copy_to_user_hvm(void *to, const void *from, unsigned len);
-unsigned long clear_user_hvm(void *to, unsigned int len);
-unsigned long copy_from_user_hvm(void *to, const void *from, unsigned len);
+unsigned int copy_to_user_hvm(void *to, const void *from, unsigned int len);
+unsigned int clear_user_hvm(void *to, unsigned int len);
+unsigned int copy_from_user_hvm(void *to, const void *from, unsigned int len);
 
 #endif /* __ASM_X86_HVM_GUEST_ACCESS_H__ */
diff --git a/xen/include/asm-x86/hvm/support.h 
b/xen/include/asm-x86/hvm/support.h
index 1500e6c94b..e161907dfa 100644
--- a/xen/include/asm-x86/hvm/support.h
+++ b/xen/include/asm-x86/hvm/support.h
@@ -70,9 +70,9 @@ enum hvm_translation_result {
  * address range does not map entirely onto ordinary machine memory.
  */
 enum hvm_translation_result hvm_copy_to_guest_phys(
-    paddr_t paddr, void *buf, int size, struct vcpu *v);
+    paddr_t paddr, void *buf, unsigned int size, struct vcpu *v);
 enum hvm_translation_result hvm_copy_from_guest_phys(
-    void *buf, paddr_t paddr, int size);
+    void *buf, paddr_t paddr, unsigned int size);
 
 /*
  * Copy to/from a guest linear address. @pfec should include PFEC_user_mode
@@ -96,10 +96,10 @@ typedef struct pagefault_info
 } pagefault_info_t;
 
 enum hvm_translation_result hvm_copy_to_guest_linear(
-    unsigned long addr, void *buf, int size, uint32_t pfec,
+    unsigned long addr, void *buf, unsigned int size, uint32_t pfec,
     pagefault_info_t *pfinfo);
 enum hvm_translation_result hvm_copy_from_guest_linear(
-    void *buf, unsigned long addr, int size, uint32_t pfec,
+    void *buf, unsigned long addr, unsigned int size, uint32_t pfec,
     pagefault_info_t *pfinfo);
 
 /*
--
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