From 5a4b0320783a19f877dd595813569b3c25f4ff81 Mon Sep 17 00:00:00 2001 From: =?utf8?q?C=C3=A9dric=20Le=20Goater?= Date: Thu, 30 Sep 2021 12:25:35 +0200 Subject: [PATCH] powerpc/pseries/msi: Add an empty irq_write_msi_msg() handler MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The IPR drivers tests for MSI support at probe time with MSI vector 0 and when done, frees the IRQ with free_irq(). This test was introduced by 95fecd90397e ("ipr: add test for MSI interrupt support") as an improvement of commit 5a9ef25b14d3 ("[SCSI] ipr: add MSI support") because a boot failure was reported on a Bimini PowerPC system: https://lore.kernel.org/r/1242926159.3007.5.camel@localhost.localdomain It was finally decided to remove MSI support on Bimini systems in 6eb0ac03899a ("powerpc/maple: Add a quirk to disable MSI for IPR on Bimini"). Linux 5.15-rc1 added MSI domain support to the pseries machine and when free_irq is called() in the driver, msi_domain_deactivate() also is. This resets the MSI table entry of the associate vector by calling __pci_write_msi_msg() with an empty message and breaks any further activation of the same vector. In the case of the IPR driver, it breaks the initialization sequence of the IOA. Introduce an empty irq_write_msi_msg() handler in the MSI domain of the pseries machine to avoid clearing the MSI vector entry. Updating the entry is not strictly necessary since it is initialized by the underlying hypervisor, PowerVM or QEMU/KVM. Fixes: a5f3d2c17b07 ("powerpc/pseries/pci: Add MSI domains") Signed-off-by: Cédric Le Goater Reported-by: Abdul Haleem Tested-by: Mahesh Salgaonkar [mpe: Tweak comment wording and formatting slightly] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210930102535.1047230-1-clg@kaod.org --- arch/powerpc/platforms/pseries/msi.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c index 1b305e4..8627362 100644 --- a/arch/powerpc/platforms/pseries/msi.c +++ b/arch/powerpc/platforms/pseries/msi.c @@ -507,12 +507,27 @@ static void pseries_msi_unmask(struct irq_data *d) irq_chip_unmask_parent(d); } +static void pseries_msi_write_msg(struct irq_data *data, struct msi_msg *msg) +{ + struct msi_desc *entry = irq_data_get_msi_desc(data); + + /* + * Do not update the MSIx vector table. It's not strictly necessary + * because the table is initialized by the underlying hypervisor, PowerVM + * or QEMU/KVM. However, if the MSIx vector entry is cleared, any further + * activation will fail. This can happen in some drivers (eg. IPR) which + * deactivate an IRQ used for testing MSI support. + */ + entry->msg = *msg; +} + static struct irq_chip pseries_pci_msi_irq_chip = { .name = "pSeries-PCI-MSI", .irq_shutdown = pseries_msi_shutdown, .irq_mask = pseries_msi_mask, .irq_unmask = pseries_msi_unmask, .irq_eoi = irq_chip_eoi_parent, + .irq_write_msi_msg = pseries_msi_write_msg, }; static struct msi_domain_info pseries_msi_domain_info = { -- 2.7.4