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Tsirkin" To: Alex Williamson Cc: marcel.apfelbaum@gmail.com, qemu-devel@nongnu.org, clg@redhat.com Subject: Re: [PATCH] pci: Add option to disable device level INTx masking Message-ID: <20240308115643-mutt-send-email-mst@kernel.org> References: <20240307184645.104349-1-alex.williamson@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240307184645.104349-1-alex.williamson@redhat.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.572, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Mar 07, 2024 at 11:46:42AM -0700, Alex Williamson wrote: > The PCI 2.3 spec added definitions of the INTx disable and status bits, > in the command and status registers respectively. The command register > bit, commonly known as DisINTx in lspci, controls whether the device > can assert the INTx signal. > > Operating systems will often write to this bit to test whether a device > supports this style of legacy interrupt masking. When using device > assignment, such as with vfio-pci, the result of this test dictates > whether the device can use a shared or exclusive interrupt (ie. generic > INTx masking at the device via DisINTx or IRQ controller level INTx > masking). > > Add an experimental option to the base set of properties for PCI > devices which allows the DisINTx bit to be excluded from wmask, making > it read-only to the guest for testing purposes related to INTx masking. > Could you clarify the use a bit more? It's unstable - do you expect to experiment with it and then make it permanent down the road? > Signed-off-by: Alex Williamson > --- > hw/pci/pci.c | 14 ++++++++++---- > include/hw/pci/pci.h | 2 ++ > 2 files changed, 12 insertions(+), 4 deletions(-) > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c > index 6496d027ca61..8c78326ad67f 100644 > --- a/hw/pci/pci.c > +++ b/hw/pci/pci.c > @@ -85,6 +85,8 @@ static Property pci_props[] = { > QEMU_PCIE_ERR_UNC_MASK_BITNR, true), > DEFINE_PROP_BIT("x-pcie-ari-nextfn-1", PCIDevice, cap_present, > QEMU_PCIE_ARI_NEXTFN_1_BITNR, false), > + DEFINE_PROP_BIT("x-pci-disintx", PCIDevice, cap_present, > + QEMU_PCI_DISINTX_BITNR, true), > DEFINE_PROP_END_OF_LIST() > }; > > @@ -861,13 +863,17 @@ static void pci_init_cmask(PCIDevice *dev) > static void pci_init_wmask(PCIDevice *dev) > { > int config_size = pci_config_size(dev); > + uint16_t cmd_wmask = PCI_COMMAND_IO | PCI_COMMAND_MEMORY | > + PCI_COMMAND_MASTER | PCI_COMMAND_SERR; > > dev->wmask[PCI_CACHE_LINE_SIZE] = 0xff; > dev->wmask[PCI_INTERRUPT_LINE] = 0xff; > - pci_set_word(dev->wmask + PCI_COMMAND, > - PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | > - PCI_COMMAND_INTX_DISABLE); > - pci_word_test_and_set_mask(dev->wmask + PCI_COMMAND, PCI_COMMAND_SERR); > + > + if (dev->cap_present & QEMU_PCI_DISINTX) { > + cmd_wmask |= PCI_COMMAND_INTX_DISABLE; > + } > + > + pci_set_word(dev->wmask + PCI_COMMAND, cmd_wmask); > > memset(dev->wmask + PCI_CONFIG_HEADER_SIZE, 0xff, > config_size - PCI_CONFIG_HEADER_SIZE); > diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h > index eaa3fc99d884..45f0fac435cc 100644 > --- a/include/hw/pci/pci.h > +++ b/include/hw/pci/pci.h > @@ -212,6 +212,8 @@ enum { > QEMU_PCIE_ERR_UNC_MASK = (1 << QEMU_PCIE_ERR_UNC_MASK_BITNR), > #define QEMU_PCIE_ARI_NEXTFN_1_BITNR 12 > QEMU_PCIE_ARI_NEXTFN_1 = (1 << QEMU_PCIE_ARI_NEXTFN_1_BITNR), > +#define QEMU_PCI_DISINTX_BITNR 13 > + QEMU_PCI_DISINTX = (1 << QEMU_PCI_DISINTX_BITNR), > }; > > typedef struct PCIINTxRoute { > -- > 2.44.0