From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Alex Williamson <alex.williamson@redhat.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Kevin Tian <kevin.tian@intel.com>, Marc Zyngier <maz@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
x86@kernel.org
Subject: [patch 4/8] PCI/MSI: Enforce MSI[X] entry updates to be visible
Date: Wed, 21 Jul 2021 21:11:30 +0200 [thread overview]
Message-ID: <20210721192650.499597025@linutronix.de> (raw)
In-Reply-To: 20210721191126.274946280@linutronix.de
Nothing enforces the posted writes to be visible when the function
returns. Flush them even if the flush might be redundant when the entry is
masked already as the unmask will flush as well. This is either setup or a
rare affinity change event so the extra flush is not the end of the world.
While this is more a theoretical issue especially the X86 MSI affinity
stter mechanism relies on the assumption that the update has reached the
hardware when the function returns.
Again, as this never has been enfocred the Fixes tag refers to a commit in:
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Fixes: f036d4ea5fa7 ("[PATCH] ia32 Message Signalled Interrupt support")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
---
drivers/pci/msi.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -311,6 +311,9 @@ void __pci_write_msi_msg(struct msi_desc
if (unmasked)
__pci_msix_desc_mask_irq(entry, 0);
+
+ /* Ensure that the writes are visible in the device */
+ readl(base + PCI_MSIX_ENTRY_DATA);
} else {
int pos = dev->msi_cap;
u16 msgctl;
@@ -331,6 +334,8 @@ void __pci_write_msi_msg(struct msi_desc
pci_write_config_word(dev, pos + PCI_MSI_DATA_32,
msg->data);
}
+ /* Ensure that the writes are visible in the device */
+ pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
}
skip:
next prev parent reply other threads:[~2021-07-21 19:28 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 19:11 [patch 0/8] PCI/MSI, x86: Cure a couple of inconsistencies Thomas Gleixner
2021-07-21 19:11 ` [patch 1/8] PCI/MSI: Enable and mask MSIX early Thomas Gleixner
2021-07-21 21:38 ` Raj, Ashok
2021-07-21 22:51 ` Thomas Gleixner
2021-07-22 21:43 ` Bjorn Helgaas
2021-07-27 20:33 ` Thomas Gleixner
2021-07-21 19:11 ` [patch 2/8] PCI/MSI: Mask all unused MSI-X entries Thomas Gleixner
2021-07-21 22:23 ` Raj, Ashok
2021-07-21 22:57 ` Thomas Gleixner
2021-07-22 13:46 ` Marc Zyngier
2021-07-28 10:04 ` Thomas Gleixner
2021-07-22 21:45 ` Bjorn Helgaas
2021-07-21 19:11 ` [patch 3/8] PCI/MSI: Enforce that MSI-X table entry is masked for update Thomas Gleixner
2021-07-21 22:32 ` Raj, Ashok
2021-07-21 22:59 ` Thomas Gleixner
2021-07-22 21:46 ` Bjorn Helgaas
2021-07-21 19:11 ` Thomas Gleixner [this message]
2021-07-22 21:48 ` [patch 4/8] PCI/MSI: Enforce MSI[X] entry updates to be visible Bjorn Helgaas
[not found] ` <CAHp75VdNi4rMuRz8UrW9Haf_Ge8KmNJ0w9ykheqkVhmpXHTUyg@mail.gmail.com>
2021-07-23 8:14 ` Marc Zyngier
2021-07-21 19:11 ` [patch 5/8] PCI/MSI: Simplify msi_verify_entries() Thomas Gleixner
2021-07-21 19:11 ` [patch 6/8] genirq: Provide IRQCHIP_AFFINITY_PRE_STARTUP Thomas Gleixner
2021-07-22 15:12 ` Marc Zyngier
2021-07-28 10:40 ` Thomas Gleixner
2021-07-21 19:11 ` [patch 7/8] x86/ioapic: Force affinity setup before startup Thomas Gleixner
2021-07-21 19:11 ` [patch 8/8] x86/msi: " Thomas Gleixner
2021-07-21 21:10 ` [patch 0/8] PCI/MSI, x86: Cure a couple of inconsistencies Raj, Ashok
2021-07-21 22:39 ` Thomas Gleixner
2021-07-22 15:17 ` Marc Zyngier
2021-07-22 21:43 ` Bjorn Helgaas
2021-07-27 20:38 ` Thomas Gleixner
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