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Commit 48005f64 authored by Jan Kiszka's avatar Jan Kiszka Committed by Avi Kivity
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KVM: x86: Save&restore interrupt shadow mask 



The interrupt shadow created by STI or MOV-SS-like operations is part of
the VCPU state and must be preserved across migration. Transfer it in
the spare padding field of kvm_vcpu_events.interrupt.

As a side effect we now have to make vmx_set_interrupt_shadow robust
against both shadow types being set. Give MOV SS a higher priority and
skip STI in that case to avoid that VMX throws a fault on next entry.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 03b82a30

Documentation/kvm/api.txt

+10 −1
Original line number Diff line number Diff line
@@ -656,6 +656,7 @@ struct kvm_clock_data { 
4.29 KVM_GET_VCPU_EVENTS



Capability: KVM_CAP_VCPU_EVENTS

Extended by: KVM_CAP_INTR_SHADOW

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_vcpu_event (out)
@@ -676,7 +677,7 @@ struct kvm_vcpu_events { 
		__u8 injected;

		__u8 nr;

		__u8 soft;

		__u8 pad;

		__u8 shadow;

	} interrupt;

	struct {

		__u8 injected;
@@ -688,9 +689,13 @@ struct kvm_vcpu_events { 
	__u32 flags;

};



KVM_VCPUEVENT_VALID_SHADOW may be set in the flags field to signal that

interrupt.shadow contains a valid state. Otherwise, this field is undefined.



4.30 KVM_SET_VCPU_EVENTS



Capability: KVM_CAP_VCPU_EVENTS

Extended by: KVM_CAP_INTR_SHADOW

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_vcpu_event (in)
@@ -709,6 +714,10 @@ current in-kernel state. The bits are: 
KVM_VCPUEVENT_VALID_NMI_PENDING - transfer nmi.pending to the kernel

KVM_VCPUEVENT_VALID_SIPI_VECTOR - transfer sipi_vector



If KVM_CAP_INTR_SHADOW is available, KVM_VCPUEVENT_VALID_SHADOW can be set in

the flags field to signal that interrupt.shadow contains a valid state and

shall be written into the VCPU.





5. The kvm_run structure

arch/x86/include/asm/kvm.h

+6 −1
Original line number Diff line number Diff line
@@ -257,6 +257,11 @@ struct kvm_reinject_control { 
/* When set in flags, include corresponding fields on KVM_SET_VCPU_EVENTS */

#define KVM_VCPUEVENT_VALID_NMI_PENDING	0x00000001

#define KVM_VCPUEVENT_VALID_SIPI_VECTOR	0x00000002

#define KVM_VCPUEVENT_VALID_SHADOW	0x00000004



/* Interrupt shadow states */

#define KVM_X86_SHADOW_INT_MOV_SS	0x01

#define KVM_X86_SHADOW_INT_STI		0x02



/* for KVM_GET/SET_VCPU_EVENTS */

struct kvm_vcpu_events {
@@ -271,7 +276,7 @@ struct kvm_vcpu_events { 
		__u8 injected;

		__u8 nr;

		__u8 soft;

		__u8 pad;

		__u8 shadow;

	} interrupt;

	struct {

		__u8 injected;

arch/x86/include/asm/kvm_emulate.h

+0 −3
Original line number Diff line number Diff line
@@ -153,9 +153,6 @@ struct decode_cache { 
	struct fetch_cache fetch;

};



#define X86_SHADOW_INT_MOV_SS  1

#define X86_SHADOW_INT_STI     2



struct x86_emulate_ctxt {

	/* Register state before/after emulation. */

	struct kvm_vcpu *vcpu;

arch/x86/kvm/emulate.c

+2 −2
Original line number Diff line number Diff line
@@ -2128,7 +2128,7 @@ special_insn: 
		}



		if (c->modrm_reg == VCPU_SREG_SS)

			toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS);

			toggle_interruptibility(ctxt, KVM_X86_SHADOW_INT_MOV_SS);



		rc = kvm_load_segment_descriptor(ctxt->vcpu, sel, c->modrm_reg);
@@ -2366,7 +2366,7 @@ special_insn: 
		if (emulator_bad_iopl(ctxt))

			kvm_inject_gp(ctxt->vcpu, 0);

		else {

			toggle_interruptibility(ctxt, X86_SHADOW_INT_STI);

			toggle_interruptibility(ctxt, KVM_X86_SHADOW_INT_STI);

			ctxt->eflags |= X86_EFLAGS_IF;

			c->dst.type = OP_NONE;	/* Disable writeback. */

		}

arch/x86/kvm/svm.c

+1 −1
Original line number Diff line number Diff line
@@ -265,7 +265,7 @@ static u32 svm_get_interrupt_shadow(struct kvm_vcpu *vcpu, int mask) 
	u32 ret = 0;



	if (svm->vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK)

		ret |= X86_SHADOW_INT_STI | X86_SHADOW_INT_MOV_SS;

		ret |= KVM_X86_SHADOW_INT_STI | KVM_X86_SHADOW_INT_MOV_SS;

	return ret & mask;

}