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KVM: VMX: Use vmx to inject real-mode interrupts

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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 <avi@qumranet.com>
This commit is contained in:
Avi Kivity
2007-11-08 18:19:20 +02:00
parent 12264760e4
commit 9c5623e3e4
2 changed files with 5 additions and 49 deletions
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53
drivers/kvm/vmx.c
View File

@@ -1709,58 +1709,13 @@ out:
return ret; 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) static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
{ {
if (vcpu->rmode.active) { 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; return;
} }
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,

1
drivers/kvm/vmx.h
View File

@@ -233,6 +233,7 @@ enum vmcs_field {
#define INTR_TYPE_EXT_INTR (0 << 8) /* external interrupt */ #define INTR_TYPE_EXT_INTR (0 << 8) /* external interrupt */
#define INTR_TYPE_EXCEPTION (3 << 8) /* processor exception */ #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 * Exit Qualifications for MOV for Control Register Access