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KVM: x86: ioapic: Preserve read-only values in the redirection table

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[ Upstream commit b200dded0a6974a3b69599832b2203483920ab25 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nikita Leshenko 2017-11-05 15:52:33 +02:00 committed by Greg Kroah-Hartman
parent 3ee7ae2bb5
commit 77e1eb750f
1 changed files with 6 additions and 0 deletions
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6
arch/x86/kvm/ioapic.c
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@ -268,6 +268,7 @@ 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) {
@ -290,6 +291,9 @@ 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;
@ -297,6 +301,8 @@ 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