linux-kernel - [PATCH v3 13/16] KVM: x86: don't assume layout of kvm_kpit

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Date:	Wed,  2 Mar 2016 22:56:50 +0100
From:	Radim Krčmář <radimkrcmar@....cz>
To:	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	Yuki Shibuya <shibuya.yk@...s.nec.co.jp>
Subject: [PATCH v3 13/16] KVM: x86: don't assume layout of kvm_kpit_state

From: Radim Krčmář <rkrcmar@...hat.com>

channels has offset 0 and correct size now, but that can change.

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/x86.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76f9f48898a5..60d6c0036a98 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3604,9 +3604,13 @@ static int kvm_vm_ioctl_set_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 
 static int kvm_vm_ioctl_get_pit(struct kvm *kvm, struct kvm_pit_state *ps)
 {
-	mutex_lock(&kvm->arch.vpit->pit_state.lock);
-	memcpy(ps, &kvm->arch.vpit->pit_state, sizeof(struct kvm_pit_state));
-	mutex_unlock(&kvm->arch.vpit->pit_state.lock);
+	struct kvm_kpit_state *kps = &kvm->arch.vpit->pit_state;
+
+	BUILD_BUG_ON(sizeof(*ps) != sizeof(kps->channels));
+
+	mutex_lock(&kps->lock);
+	memcpy(ps, &kps->channels, sizeof(*ps));
+	mutex_unlock(&kps->lock);
 	return 0;
 }
 
@@ -3616,7 +3620,7 @@ static int kvm_vm_ioctl_set_pit(struct kvm *kvm, struct kvm_pit_state *ps)
 	struct kvm_pit *pit = kvm->arch.vpit;
 
 	mutex_lock(&pit->pit_state.lock);
-	memcpy(&pit->pit_state, ps, sizeof(struct kvm_pit_state));
+	memcpy(&pit->pit_state.channels, ps, sizeof(*ps));
 	for (i = 0; i < 3; i++)
 		kvm_pit_load_count(pit, i, ps->channels[i].count, 0);
 	mutex_unlock(&pit->pit_state.lock);
-- 
2.7.2