From: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
According to the hardware manual, when the Poll command is issued, the
byte returned by the I/O read is 1 in Bit 7 when there is an interrupt,
and the highest priority binary code in Bits 2:0. The current pic
simulation code is not implemented strictly according to the above
expression.
Fix the implementation of pic_poll_read(), set Bit 7 when there is an
interrupt.
Signed-off-by: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
---
V2 -> V3: Keep the return value(0x07) unchanged if there's no interrupt
V1 -> V2: Keep the logic of pic_poll_read(), only fix the return value
arch/x86/kvm/i8259.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 4756bcb5724f..8dec646e764b 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -411,7 +411,10 @@ static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
pic_clear_isr(s, ret);
if (addr1 >> 7 || ret != 2)
pic_update_irq(s->pics_state);
+ /* Bit 7 is 1, means there's an interrupt */
+ ret |= 0x80;
} else {
+ /* Bit 7 is 0, means there's no interrupt */
ret = 0x07;
pic_update_irq(s->pics_state);
}
--
2.31.1
