From b200dded0a6974a3b69599832b2203483920ab25 Mon Sep 17 00:00:00 2001 From: Nikita Leshenko Date: Sun, 5 Nov 2017 15:52:33 +0200 Subject: [PATCH] KVM: x86: ioapic: Preserve read-only values in the redirection table MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit According to 82093AA (IOAPIC) manual, Remote IRR and Delivery Status are read-only. QEMU implements the bits as RO in commit 479c2a1cb7fb ("ioapic: keep RO bits for IOAPIC entry"). Signed-off-by: Nikita Leshenko Reviewed-by: Liran Alon Signed-off-by: Konrad Rzeszutek Wilk Reviewed-by: Wanpeng Li Reviewed-by: Steve Rutherford Signed-off-by: Radim Krčmář --- arch/x86/kvm/ioapic.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c index 163d340ee5f8..4e822ad363f3 100644 --- a/arch/x86/kvm/ioapic.c +++ b/arch/x86/kvm/ioapic.c @@ -276,6 +276,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) { unsigned index; bool mask_before, mask_after; + int old_remote_irr, old_delivery_status; union kvm_ioapic_redirect_entry *e; switch (ioapic->ioregsel) { @@ -298,6 +299,9 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) return; e = &ioapic->redirtbl[index]; mask_before = e->fields.mask; + /* Preserve read-only fields */ + old_remote_irr = e->fields.remote_irr; + old_delivery_status = e->fields.delivery_status; if (ioapic->ioregsel & 1) { e->bits &= 0xffffffff; e->bits |= (u64) val << 32; @@ -305,6 +309,8 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) e->bits &= ~0xffffffffULL; e->bits |= (u32) val; } + e->fields.remote_irr = old_remote_irr; + e->fields.delivery_status = old_delivery_status; /* * Some OSes (Linux, Xen) assume that Remote IRR bit will