Amit Shah wrote:
* Anthony Liguori wrote:
Amit Shah wrote:
* Anthony Liguori wrote:
This patch refactors the current hypercall infrastructure to better
support live migration and SMP. It eliminates the hypercall page by
trapping the UD exception that would occur if you used the wrong
hypercall instruction for the underlying architecture and replacing it
with the right one lazily.
This doesn't work right for SVM. It keeps looping indefinitely; on a
kvm_stat run, I get about 230,000 light vm exits per second, with the
hypercall never returning to the guest.
...
What are you using to issue the hypercall?
+ r = kvm_hypercall1(KVM_PV_PCI_DEVICE, page_gfn);
Setup is done by:
+ if (!kvm_para_available()) {
+ printk(KERN_ERR "KVM paravirt support not available\n");
+ r = -ENODEV;
+ goto out_dereg;
+ }
There was a bug where instructions with a modrm byte specifying a
register would try to access memory. In the memory was not mapped,
emulation would fail. vmcall is one such instruction. This was fixed by
commit f83562246921d6a8a7de8b76853a6835ace3699d
Author: Aurelien Jarno <[email protected]>
Date: Wed Oct 17 19:30:41 2007 +0200
KVM: x86 emulator: fix access registers for instructions with ModR/M
byte and Mod = 3
The patch belows changes the access type to register from memory for
instructions that are declared as SrcMem or DstMem, but have a
ModR/M byte with Mod = 3.
It fixes (at least) the lmsw and smsw instructions on an AMD64 CPU,
which are needed for FreeBSD.
Signed-off-by: Aurelien Jarno <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 7c95ae5..8c50496 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -835,6 +835,14 @@ modrm_done:
if (c->twobyte && c->b == 0x01
&& c->modrm_reg == 7)
break;
+ /*
+ * For instructions with a ModR/M byte, switch to register
+ * access if Mod = 3.
+ */
+ if ((c->d & ModRM) && c->modrm_mod == 3) {
+ c->src.type = OP_REG;
+ break;
+ }
srcmem_common:
c->src.type = OP_MEM;
break;
@@ -897,7 +905,14 @@ srcmem_common:
}
break;
case DstMem:
- c->dst.type = OP_MEM;
+ /*
+ * For instructions with a ModR/M byte, switch to register
+ * access if Mod = 3.
+ */
+ if ((c->d & ModRM) && c->modrm_mod == 3)
+ c->dst.type = OP_REG;
+ else
+ c->dst.type = OP_MEM;
break;
}
--
error compiling committee.c: too many arguments to function
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