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Re: [PATCH v3 2/3] pci: Honour wmask when resetting PCI_INTERRUPT_LINE

From: BALATON Zoltan
Subject: Re: [PATCH v3 2/3] pci: Honour wmask when resetting PCI_INTERRUPT_LINE
Date: Tue, 10 Mar 2020 19:20:58 +0100 (CET)
User-agent: Alpine 2.22 (BSF 395 2020-01-19)

On Tue, 10 Mar 2020, Mark Cave-Ayland wrote:
On 09/03/2020 20:54, BALATON Zoltan wrote:
On Mon, 9 Mar 2020, Michael S. Tsirkin wrote:
On Mon, Mar 09, 2020 at 08:18:13PM +0100, BALATON Zoltan wrote:
The pci_do_device_reset() function (called from pci_device_reset)
clears the PCI_INTERRUPT_LINE config reg of devices on the bus but did
this without taking wmask into account. We'll have a device model now
that needs to set a constant value for this reg and this patch allows
to do that without additional workaround in device emulation to
reverse the effect of this PCI bus reset function.

Suggested-by: Mark Cave-Ayland <address@hidden>
Signed-off-by: BALATON Zoltan <address@hidden>
 hw/pci/pci.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index e1ed6677e1..d07e4ed9de 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -302,8 +302,10 @@ static void pci_do_device_reset(PCIDevice *dev)
     pci_word_test_and_clear_mask(dev->config + PCI_STATUS,
                                  pci_get_word(dev->wmask + PCI_STATUS) |
                                  pci_get_word(dev->w1cmask + PCI_STATUS));
+    pci_word_test_and_clear_mask(dev->config + PCI_INTERRUPT_LINE,
+                              pci_get_word(dev->wmask + PCI_INTERRUPT_LINE) |
+                              pci_get_word(dev->w1cmask + PCI_INTERRUPT_LINE));

PCI spec says:

Interrupt Line
The Interrupt Line register is an eight-bit register used to communicate 
line routing

I don't see how it makes sense to access it as a word.

Patch actually comes from Mark, I don't know. Should we change it to
pci_byte_test_and_clear_mask or what's the appropriate way here?

Ooops yes it should pci_byte_test_and_clear_mask(). Clearly I got a bit too 
from copying the existing examples in pci_do_device_reset().

OK will test it and send updated version.


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