KVM: x86: ioapic: Preserve read-only values in the redirection table
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 <nikita.leshchenko@oracle.com> Reviewed-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com> Reviewed-by: Steve Rutherford <srutherford@google.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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@ -276,6 +276,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
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{
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unsigned index;
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bool mask_before, mask_after;
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int old_remote_irr, old_delivery_status;
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union kvm_ioapic_redirect_entry *e;
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switch (ioapic->ioregsel) {
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@ -298,6 +299,9 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
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return;
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e = &ioapic->redirtbl[index];
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mask_before = e->fields.mask;
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/* Preserve read-only fields */
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old_remote_irr = e->fields.remote_irr;
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old_delivery_status = e->fields.delivery_status;
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if (ioapic->ioregsel & 1) {
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e->bits &= 0xffffffff;
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e->bits |= (u64) val << 32;
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@ -305,6 +309,8 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
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e->bits &= ~0xffffffffULL;
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e->bits |= (u32) val;
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}
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e->fields.remote_irr = old_remote_irr;
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e->fields.delivery_status = old_delivery_status;
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/*
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* Some OSes (Linux, Xen) assume that Remote IRR bit will
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