linux-kernel - [PATCH kvm] KVM: i8259: Fix poll command

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Message-Id: <20230402044520.2125966-1-alexjlzheng@tencent.com>
Date:   Sun,  2 Apr 2023 12:45:20 +0800
From:   Jinliang Zheng <alexjlzheng@...il.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jinliang Zheng <alexjlzheng@...cent.com>
Subject: [PATCH kvm] KVM: i8259: 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 poll mode in pic simulation by pic_intack,
and remove redundant pic_poll_read code.

Signed-off-by: Jinliang Zheng <alexjlzheng@...cent.com>
---
 arch/x86/kvm/i8259.c | 29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 4756bcb5724f..bc5b758e8f73 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -397,35 +397,18 @@ static void pic_ioport_write(void *opaque, u32 addr, u32 val)
 		}
 }
 
-static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
-{
-	int ret;
-
-	ret = pic_get_irq(s);
-	if (ret >= 0) {
-		if (addr1 >> 7) {
-			s->pics_state->pics[0].isr &= ~(1 << 2);
-			s->pics_state->pics[0].irr &= ~(1 << 2);
-		}
-		s->irr &= ~(1 << ret);
-		pic_clear_isr(s, ret);
-		if (addr1 >> 7 || ret != 2)
-			pic_update_irq(s->pics_state);
-	} else {
-		ret = 0x07;
-		pic_update_irq(s->pics_state);
-	}
-
-	return ret;
-}
-
 static u32 pic_ioport_read(void *opaque, u32 addr)
 {
 	struct kvm_kpic_state *s = opaque;
 	int ret;
 
 	if (s->poll) {
-		ret = pic_poll_read(s, addr);
+		ret = pic_get_irq(s);
+		if (ret >= 0) {
+			pic_intack(s, ret);
+			ret |= 0x80;
+		} else
+			ret = 0;
 		s->poll = 0;
 	} else
 		if ((addr & 1) == 0)
-- 
2.37.3