[PATCH v1 5/9] KVM: x86: Refactor APIC state get/set to accept variable-sized buffers

[Manali Shukla <manali.shukla@amd.com>]

Refactor kvm_apic_get_state() and kvm_apic_set_state() to accept a void
pointer and explicit size parameter instead of struct kvm_lapic_state.
This removes the hard-coded assumption about 1KB APIC register space and
allows functions to work with both 1KB and 4KB APIC register space.

Existing callers of kvm_apic_get_state() and kvm_apic_set_state() pass
`s->regs` and `sizeof(*s)` to maintain the current behavior with the 1KB
kvm_lapic_state structure.  Subsequent patches will add KVM_GET_LAPIC2
and KVM_SET_LAPIC2 IOCTLs that will also use these functions in order to
save/restore 4KB APIC register space.

No functional change intended; existing KVM_GET_LAPIC and KVM_SET_LAPIC
IOCTLs work exactly as before.

Signed-off-by: Manali Shukla <manali.shukla@amd.com>
---
 arch/x86/kvm/lapic.c | 32 ++++++++++++++++----------------
 arch/x86/kvm/lapic.h |  4 ++--
 arch/x86/kvm/x86.c   |  4 ++--
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 66819397e073..4ed6abb414e4 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -3151,12 +3151,12 @@ void kvm_apic_ack_interrupt(struct kvm_vcpu *vcpu, int vector)
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_apic_ack_interrupt);
 
 static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
-		struct kvm_lapic_state *s, bool set)
+		void *regs, bool set)
 {
 	if (apic_x2apic_mode(vcpu->arch.apic)) {
 		u32 x2apic_id = kvm_x2apic_id(vcpu->arch.apic);
-		u32 *id = (u32 *)(s->regs + APIC_ID);
-		u32 *ldr = (u32 *)(s->regs + APIC_LDR);
+		u32 *id = (u32 *)(regs + APIC_ID);
+		u32 *ldr = (u32 *)(regs + APIC_LDR);
 		u64 icr;
 
 		if (vcpu->kvm->arch.x2apic_format) {
@@ -3189,12 +3189,12 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
 
 		if (!kvm_x86_ops.x2apic_icr_is_split) {
 			if (set) {
-				icr = apic_get_reg(s->regs, APIC_ICR) |
-				      (u64)apic_get_reg(s->regs, APIC_ICR2) << 32;
-				apic_set_reg64(s->regs, APIC_ICR, icr);
+				icr = apic_get_reg(regs, APIC_ICR) |
+				      (u64)apic_get_reg(regs, APIC_ICR2) << 32;
+				apic_set_reg64(regs, APIC_ICR, icr);
 			} else {
-				icr = apic_get_reg64(s->regs, APIC_ICR);
-				apic_set_reg(s->regs, APIC_ICR2, icr >> 32);
+				icr = apic_get_reg64(regs, APIC_ICR);
+				apic_set_reg(regs, APIC_ICR2, icr >> 32);
 			}
 		}
 	}
@@ -3202,20 +3202,20 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
-int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
+int kvm_apic_get_state(struct kvm_vcpu *vcpu, void *regs, unsigned int size)
 {
-	memcpy(s->regs, vcpu->arch.apic->regs, sizeof(*s));
+	memcpy(regs, vcpu->arch.apic->regs, size);
 
 	/*
 	 * Get calculated timer current count for remaining timer period (if
 	 * any) and store it in the returned register set.
 	 */
-	apic_set_reg(s->regs, APIC_TMCCT, __apic_read(vcpu->arch.apic, APIC_TMCCT));
+	apic_set_reg(regs, APIC_TMCCT, __apic_read(vcpu->arch.apic, APIC_TMCCT));
 
-	return kvm_apic_state_fixup(vcpu, s, false);
+	return kvm_apic_state_fixup(vcpu, regs, false);
 }
 
-int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
+int kvm_apic_set_state(struct kvm_vcpu *vcpu, void *regs, unsigned int size)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	int r;
@@ -3223,14 +3223,14 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
 	kvm_x86_call(apicv_pre_state_restore)(vcpu);
 
 	/* set SPIV separately to get count of SW disabled APICs right */
-	apic_set_spiv(apic, *((u32 *)(s->regs + APIC_SPIV)));
+	apic_set_spiv(apic, *((u32 *)(regs + APIC_SPIV)));
 
-	r = kvm_apic_state_fixup(vcpu, s, true);
+	r = kvm_apic_state_fixup(vcpu, regs, true);
 	if (r) {
 		kvm_recalculate_apic_map(vcpu->kvm);
 		return r;
 	}
-	memcpy(vcpu->arch.apic->regs, s->regs, sizeof(*s));
+	memcpy(vcpu->arch.apic->regs, regs, size);
 
 	atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY);
 	kvm_recalculate_apic_map(vcpu->kvm);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 152f17903ff0..c6ac40c76f62 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -132,8 +132,8 @@ static inline int kvm_irq_delivery_to_apic(struct kvm *kvm,
 void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high);
 
 int kvm_apic_set_base(struct kvm_vcpu *vcpu, u64 value, bool host_initiated);
-int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
-int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
+int kvm_apic_get_state(struct kvm_vcpu *vcpu, void *regs, unsigned int size);
+int kvm_apic_set_state(struct kvm_vcpu *vcpu, void *regs, unsigned int size);
 int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
 
 u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 368ee9276366..669c894f1061 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5328,7 +5328,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
 
 	kvm_x86_call(sync_pir_to_irr)(vcpu);
 
-	return kvm_apic_get_state(vcpu, s);
+	return kvm_apic_get_state(vcpu, s->regs, sizeof(*s));
 }
 
 static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
@@ -5339,7 +5339,7 @@ static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
 	if (vcpu->arch.apic->guest_apic_protected)
 		return -EINVAL;
 
-	r = kvm_apic_set_state(vcpu, s);
+	r = kvm_apic_set_state(vcpu, s->regs, sizeof(*s));
 	if (r)
 		return r;
 	update_cr8_intercept(vcpu);
-- 
2.43.0