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Commit b200dded authored by Nikita Leshenko's avatar Nikita Leshenko Committed by Paolo Bonzini
Browse files

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: default avatarNikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: default avatarSteve Rutherford <srutherford@google.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent a8bfec29

arch/x86/kvm/ioapic.c

+6 −0
Original line number Diff line number Diff line
@@ -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