[Xen-changelog] [xen-unstable] [VMXASSIST] Fix GDTR accesses when paging mode enabled.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID f5b9b8439012c49306069539aa8637d1a56a9b7d
# Parent  3aad3abca9939fe69bea5395a36ecfd907e86400
[VMXASSIST] Fix GDTR accesses when paging mode enabled.

The gdtr information in oldctx is an address for guest, not for
vmxassist. When access descriptor on guest gdt, we need to go through
guest page table if guest enable paging. This error may happen if
guest enable PE/PG in one instruction.

Signed-off-by: Yunhong Jiang <yunhong.jiang@xxxxxxxxx>=20
Signed-off-by: Xin Li <xin.b.li@xxxxxxxxx>
---
 tools/firmware/vmxassist/vm86.c |   31 ++++++++++++++++++++++++++++---
 1 files changed, 28 insertions(+), 3 deletions(-)

diff -r 3aad3abca993 -r f5b9b8439012 tools/firmware/vmxassist/vm86.c
--- a/tools/firmware/vmxassist/vm86.c   Wed Aug 02 09:58:06 2006 +0100
+++ b/tools/firmware/vmxassist/vm86.c   Wed Aug 02 10:03:04 2006 +0100
@@ -52,6 +52,31 @@ static char *rnames[] = { "ax", "cx", "d
 static char *rnames[] = { "ax", "cx", "dx", "bx", "sp", "bp", "si", "di" };
 #endif /* DEBUG */
 
+#define PT_ENTRY_PRESENT 0x1
+
+static unsigned
+guest_linear_to_real(unsigned long base, unsigned off)
+{
+       unsigned int gcr3 = oldctx.cr3;
+       unsigned int l1_mfn;
+       unsigned int l0_mfn;
+
+       if (!(oldctx.cr0 & CR0_PG))
+               return base + off;
+
+       l1_mfn = ((unsigned int *)gcr3)[(base >> 22) & 0x3ff ];
+       if (!(l1_mfn & PT_ENTRY_PRESENT))
+               panic("l2 entry not present\n");
+       l1_mfn = l1_mfn & 0xfffff000 ;
+
+       l0_mfn = ((unsigned int *)l1_mfn)[(base >> 12) & 0x3ff];
+       if (!(l0_mfn & PT_ENTRY_PRESENT))
+               panic("l1 entry not present\n");
+       l0_mfn = l0_mfn & 0xfffff000;
+
+       return l0_mfn + off + (base & 0xfff);
+}
+
 static unsigned
 address(struct regs *regs, unsigned seg, unsigned off)
 {
@@ -70,7 +95,7 @@ address(struct regs *regs, unsigned seg,
            (mode == VM86_REAL_TO_PROTECTED && regs->cs == seg))
                return ((seg & 0xFFFF) << 4) + off;
 
-       entry = ((unsigned long long *) oldctx.gdtr_base)[seg >> 3];
+       entry = ((unsigned long long *) guest_linear_to_real(oldctx.gdtr_base, 
0))[seg >> 3];
        entry_high = entry >> 32;
        entry_low = entry & 0xFFFFFFFF;
 
@@ -94,7 +119,7 @@ trace(struct regs *regs, int adjust, cha
 trace(struct regs *regs, int adjust, char *fmt, ...)
 {
        unsigned off = regs->eip - adjust;
-        va_list ap;
+       va_list ap;
 
        if ((traceset & (1 << mode)) &&
           (mode == VM86_REAL_TO_PROTECTED || mode == VM86_REAL)) {
@@ -755,7 +780,7 @@ load_seg(unsigned long sel, uint32_t *ba
                return 1;
        }
 
-       entry =  ((unsigned long long *) oldctx.gdtr_base)[sel >> 3];
+       entry = ((unsigned long long *) guest_linear_to_real(oldctx.gdtr_base, 
0))[sel >> 3];
 
        /* Check the P bit first */
        if (!((entry >> (15+32)) & 0x1) && sel != 0)

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog