Instead of injecting real-mode interrupts by writing the interrupt frame into
guest memory, abuse vmx by injecting a software interrupt. We need to
pretend the software interrupt instruction had a length > 0, so we have to
adjust rip backward.
This lets us not to mess with writing guest memory, which is complex and also
sleeps.
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
---
drivers/kvm/vmx.c | 53 ++++-------------------------------------------------
drivers/kvm/vmx.h | 1 +
2 files changed, 5 insertions(+), 49 deletions(-)
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 6fc981d..1166132 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1709,58 +1709,13 @@ out:
return ret;
}
-static void inject_rmode_irq(struct kvm_vcpu *vcpu, int irq)
-{
- u16 ent[2];
- u16 cs;
- u16 ip;
- unsigned long flags;
- unsigned long ss_base = vmcs_readl(GUEST_SS_BASE);
- u16 sp = vmcs_readl(GUEST_RSP);
- u32 ss_limit = vmcs_read32(GUEST_SS_LIMIT);
-
- if (sp > ss_limit || sp < 6) {
- vcpu_printf(vcpu, "%s: #SS, rsp 0x%lx ss 0x%lx limit 0x%x\n",
- __FUNCTION__,
- vmcs_readl(GUEST_RSP),
- vmcs_readl(GUEST_SS_BASE),
- vmcs_read32(GUEST_SS_LIMIT));
- return;
- }
-
- if (emulator_read_std(irq * sizeof(ent), &ent, sizeof(ent), vcpu) !=
- X86EMUL_CONTINUE) {
- vcpu_printf(vcpu, "%s: read guest err\n", __FUNCTION__);
- return;
- }
-
- flags = vmcs_readl(GUEST_RFLAGS);
- cs = vmcs_readl(GUEST_CS_BASE) >> 4;
- ip = vmcs_readl(GUEST_RIP);
-
-
- if (emulator_write_emulated(
- ss_base + sp - 2, &flags, 2, vcpu) != X86EMUL_CONTINUE ||
- emulator_write_emulated(
- ss_base + sp - 4, &cs, 2, vcpu) != X86EMUL_CONTINUE ||
- emulator_write_emulated(
- ss_base + sp - 6, &ip, 2, vcpu) != X86EMUL_CONTINUE) {
- vcpu_printf(vcpu, "%s: write guest err\n", __FUNCTION__);
- return;
- }
-
- vmcs_writel(GUEST_RFLAGS, flags &
- ~(X86_EFLAGS_IF | X86_EFLAGS_AC | X86_EFLAGS_TF));
- vmcs_write16(GUEST_CS_SELECTOR, ent[1]) ;
- vmcs_writel(GUEST_CS_BASE, ent[1] << 4);
- vmcs_writel(GUEST_RIP, ent[0]);
- vmcs_writel(GUEST_RSP, (vmcs_readl(GUEST_RSP) & ~0xffff) | (sp - 6));
-}
-
static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
{
if (vcpu->rmode.active) {
- inject_rmode_irq(vcpu, irq);
+ vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
+ irq | INTR_TYPE_SOFT_INTR | INTR_INFO_VALID_MASK);
+ vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, 1);
+ vmcs_writel(GUEST_RIP, vmcs_readl(GUEST_RIP) - 1);
return;
}
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
diff --git a/drivers/kvm/vmx.h b/drivers/kvm/vmx.h
index c84bd37..d757b36 100644
--- a/drivers/kvm/vmx.h
+++ b/drivers/kvm/vmx.h
@@ -233,6 +233,7 @@ enum vmcs_field {
#define INTR_TYPE_EXT_INTR (0 << 8) /* external interrupt */
#define INTR_TYPE_EXCEPTION (3 << 8) /* processor exception */
+#define INTR_TYPE_SOFT_INTR (4 << 8) /* software interrupt */
/*
* Exit Qualifications for MOV for Control Register Access
--
1.5.3.7
-------------------------------------------------------------------------
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