[Xen-changelog] [xen stable-4.6] hvmloader: avoid tests when they would clobber used memory

[patchbot@xxxxxxx]

commit 568490750cfc36bf584d88756914f46ef3556c56
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jun 21 11:58:24 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jun 21 11:58:24 2019 +0200

    hvmloader: avoid tests when they would clobber used memory
    
    First of all limit the memory range used for testing to 4Mb: There's no
    point placing page tables right above 8Mb when they can equally well
    live at the bottom of the chunk at 4Mb - rep_io_test() cares about the
    5Mb...7Mb range only anyway. In a subsequent patch this will then also
    allow simply looking for an unused 4Mb range (instead of using a build
    time determined one).
    
    Extend the "skip tests" condition beyond the "is there enough memory"
    question.
    
    Reported-by: Charles Arnold <carnold@xxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Tested-by: Gary Lin <glin@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 0d6968635ce51a8ed7508ddcf17b3d13a462cb27
    master date: 2017-05-19 16:04:38 +0200
---
 tools/firmware/hvmloader/tests.c | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/tools/firmware/hvmloader/tests.c b/tools/firmware/hvmloader/tests.c
index fea3ad34a3..e7de974dfc 100644
--- a/tools/firmware/hvmloader/tests.c
+++ b/tools/firmware/hvmloader/tests.c
@@ -19,6 +19,7 @@
  * this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
 #include "util.h"
 
 #define TEST_FAIL 0
@@ -28,11 +29,13 @@
 /*
  * Memory layout during tests:
  *  4MB to 8MB is cleared.
- *  Page directory resides at 8MB.
- *  4 page table pages reside at 8MB+4kB to 8MB+20kB.
- *  Pagetables identity-map 0-16MB, except 4kB at va 6MB maps to pa 5MB.
+ *  Page directory resides at 4MB.
+ *  2 page table pages reside at 4MB+4kB to 4MB+12kB.
+ *  Pagetables identity-map 0-8MB, except 4kB at va 6MB maps to pa 5MB.
  */
-#define PD_START (8ul << 20)
+#define TEST_MEM_BASE (4ul << 20)
+#define TEST_MEM_SIZE (4ul << 20)
+#define PD_START TEST_MEM_BASE
 #define PT_START (PD_START + 4096)
 
 static void setup_paging(void)
@@ -41,10 +44,10 @@ static void setup_paging(void)
     uint32_t *pt = (uint32_t *)PT_START;
     uint32_t i;
 
-    /* Identity map 0-16MB. */
-    for ( i = 0; i < 4; i++ )
+    /* Identity map 0-8MB. */
+    for ( i = 0; i < 2; i++ )
         pd[i] = (unsigned long)pt + (i<<12) + 3;
-    for ( i = 0; i < (4*1024); i++ )
+    for ( i = 0; i < 2 * 1024; i++ )
         pt[i] = (i << 12) + 3;
 
     /* Page at virtual 6MB maps to physical 5MB. */
@@ -112,7 +115,7 @@ static int rep_io_test(void)
     stop_paging();
 
     i = 0;
-    for ( p = (uint32_t *)0x400000ul; p < (uint32_t *)0x700000ul; p++ )
+    for ( p = (uint32_t *)0x4ff000ul; p < (uint32_t *)0x602000ul; p++ )
     {
         uint32_t expected = 0;
         if ( check[i].addr == (unsigned long)p )
@@ -144,12 +147,12 @@ static int shadow_gs_test(void)
     if ( !(edx & (1u<<29)) )
         return TEST_SKIP;
 
-    /* Long mode pagetable setup: Identity map 0-16MB with 2MB mappings. */
+    /* Long mode pagetable setup: Identity map 0-8MB with 2MB mappings. */
     *pd = (unsigned long)pd + 0x1007; /* Level 4 */
     pd += 512;
     *pd = (unsigned long)pd + 0x1007; /* Level 3 */
     pd += 512;
-    for ( i = 0; i < 8; i++ )         /* Level 2 */
+    for ( i = 0; i < 4; i++ )         /* Level 2 */
         *pd++ = (i << 21) + 0x1e3;
 
     asm volatile (
@@ -191,8 +194,7 @@ static int shadow_gs_test(void)
 
 void perform_tests(void)
 {
-    int i, passed, skipped;
-
+    unsigned int i, passed, skipped;
     static struct {
         int (* const test)(void);
         const char *description;
@@ -204,9 +206,18 @@ void perform_tests(void)
 
     printf("Testing HVM environment:\n");
 
-    if ( hvm_info->low_mem_pgend < 0x1000 )
+    BUILD_BUG_ON(SCRATCH_PHYSICAL_ADDRESS > HVMLOADER_PHYSICAL_ADDRESS);
+    if ( hvm_info->low_mem_pgend <
+         ((TEST_MEM_BASE + TEST_MEM_SIZE) >> PAGE_SHIFT) )
+    {
+        printf("Skipping tests due to insufficient memory (<%luMB)\n",
+               (TEST_MEM_BASE + TEST_MEM_SIZE) >> 20);
+        return;
+    }
+
+    if ( (unsigned long)_end > TEST_MEM_BASE )
     {
-        printf("Skipping tests due to insufficient memory (<16MB)\n");
+        printf("Skipping tests due to overlap with base image\n");
         return;
     }
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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