Il Mon, Jun 18, 2007 at 02:32:39PM +0300, Avi Kivity ha scritto:
> >Unfortunately, this kills Windows XP (first run with a guest crash,
> >second with a host oops), so I reverted it. I'd guess some operation
> >which doesn't need writeback ends up in the modified code.
> >Previously, the check caused it to skip writeback, but now it writes
> >back random memory, causing a crash.
> >
>
> There are comments around like
>
> > /* Disable writeback. */
> > dst.orig_val = dst.val;
>
> Best option is probably to add an explicit disable_writeback flag and
> set it there.
I've tested this patch with linux, solaris and winxp, on a 32 bit guest.
So far everything is fine ;)
David, this patch should fix the lockup you're seeing.
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 633c2ed..9b7b0b9 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1139,8 +1139,10 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
return 0;
mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT);
virt = kmap_atomic(page, KM_USER0);
- kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes);
- memcpy(virt + offset_in_page(gpa), val, bytes);
+ if (memcmp(virt + offset_in_page(gpa), val, bytes)) {
+ kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes);
+ memcpy(virt + offset_in_page(gpa), val, bytes);
+ }
kunmap_atomic(virt, KM_USER0);
return 1;
}
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index a4a8481..eb10448 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -482,6 +482,7 @@ x86_emulate_memop(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
int mode = ctxt->mode;
unsigned long modrm_ea;
int use_modrm_ea, index_reg = 0, base_reg = 0, scale, rip_relative = 0;
+ int no_wb = 0;
/* Shadow copy of register state. Committed on successful emulation. */
unsigned long _regs[NR_VCPU_REGS];
@@ -1048,7 +1049,7 @@ done_prefixes:
_regs[VCPU_REGS_RSP]),
&dst.val, dst.bytes, ctxt)) != 0)
goto done;
- dst.val = dst.orig_val; /* skanky: disable writeback */
+ no_wb = 1; /* skanky: disable writeback */
break;
default:
goto cannot_emulate;
@@ -1057,7 +1058,7 @@ done_prefixes:
}
writeback:
- if ((d & Mov) || (dst.orig_val != dst.val)) {
+ if (!no_wb) {
switch (dst.type) {
case OP_REG:
/* The 4-byte case *is* correct: in 64-bit mode we zero-extend. */
@@ -1306,7 +1307,7 @@ twobyte_insn:
twobyte_special_insn:
/* Disable writeback. */
- dst.orig_val = dst.val;
+ no_wb = 1;
switch (b) {
case 0x09: /* wbinvd */
break;
Luca
--
"Ci sono le balle, le megaballe e le statistiche".
Mark Twain
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