[kvm-unit-tests,v1,2/2] x86: pku: fix the test to work with new allocator

Commit Message

Claudio Imbrenda Jan. 21, 2021, 11:18 a.m. UTC

The test used to simply take a chunk of memory and use it, hoping the
memory allocator would never touch it. The memory area used was exactly
at the beginning of the 16M boundary.

The new allocator stores metadata information there, and could cause the
test to fail.

This patch uses the new features of the allocator to properly reserve
a memory block. To make things easier and cleaner, the memory area used
is now smaller and starts at 8M.

Signed-off-by: Claudio Imbrenda <[e-mail]>
---
 x86/pku.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Patch

diff --git a/x86/pku.c b/x86/pku.c
index 4f6086c..7e8247c 100644
--- a/x86/pku.c
+++ b/x86/pku.c
@@ -1,4 +1,5 @@ 
 #include "libcflat.h"
+#include <alloc_page.h>
 #include "x86/desc.h"
 #include "x86/processor.h"
 #include "x86/vm.h"
@@ -6,7 +7,7 @@ 
 
 #define CR0_WP_MASK      (1UL << 16)
 #define PTE_PKEY_BIT     59
-#define USER_BASE        (1 << 24)
+#define USER_BASE        (1 << 23)
 #define USER_VAR(v)      (*((__typeof__(&(v))) (((unsigned long)&v) + USER_BASE)))
 
 volatile int pf_count = 0;
@@ -77,6 +78,8 @@  int main(int ac, char **av)
     set_intr_alt_stack(14, pf_tss);
     wrmsr(MSR_EFER, rdmsr(MSR_EFER) | EFER_LMA);
 
+    if (reserve_pages(USER_BASE, USER_BASE >> 12))
+        report_abort("Could not reserve memory");
     for (i = 0; i < USER_BASE; i += PAGE_SIZE) {
         *get_pte(phys_to_virt(read_cr3()), phys_to_virt(i)) &= ~PT_USER_MASK;
         *get_pte(phys_to_virt(read_cr3()), phys_to_virt(i)) |= ((unsigned long)pkey << PTE_PKEY_BIT);