Commit 9c5623e3 authored by Avi Kivity's avatar Avi Kivity
Browse files

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



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: default avatarAvi Kivity <avi@qumranet.com>
parent 12264760

drivers/kvm/vmx.c

+4 −49
Original line number Diff line number Diff line
@@ -1709,58 +1709,13 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu) 
	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,

drivers/kvm/vmx.h

+1 −0
Original line number Diff line number Diff line
@@ -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