Commit 0d42522b authored by Jinliang Zheng's avatar Jinliang Zheng Committed by Sean Christopherson
Browse files

KVM: x86: Fix poll command 



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: default avatarJinliang Zheng <alexjlzheng@tencent.com>
Link: https://lore.kernel.org/r/20230419021924.1342184-1-alexjlzheng@tencent.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent dee32197

arch/x86/kvm/i8259.c

+3 −0
Original line number Diff line number Diff line
@@ -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);

	}