From ec25d05e1893bbadc747bd0f13fe62481bc422d8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 29 Jul 2021 23:51:47 +0200 Subject: PCI/MSI: Protect msi_desc::masked for multi-MSI commit 77e89afc25f30abd56e76a809ee2884d7c1b63ce upstream. Multi-MSI uses a single MSI descriptor and there is a single mask register when the device supports per vector masking. To avoid reading back the mask register the value is cached in the MSI descriptor and updates are done by clearing and setting bits in the cache and writing it to the device. But nothing protects msi_desc::masked and the mask register from being modified concurrently on two different CPUs for two different Linux interrupts which belong to the same multi-MSI descriptor. Add a lock to struct device and protect any operation on the mask and the mask register with it. This makes the update of msi_desc::masked unconditional, but there is no place which requires a modification of the hardware register without updating the masked cache. msi_mask_irq() is now an empty wrapper which will be cleaned up in follow up changes. The problem goes way back to the initial support of multi-MSI, but picking the commit which introduced the mask cache is a valid cut off point (2.6.30). Fixes: f2440d9acbe8 ("PCI MSI: Refactor interrupt masking code") Signed-off-by: Thomas Gleixner Tested-by: Marc Zyngier Reviewed-by: Marc Zyngier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210729222542.726833414@linutronix.de Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 297239a08bb7..3414b5a67b46 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1260,6 +1260,7 @@ struct device { struct dev_pin_info *pins; #endif #ifdef CONFIG_GENERIC_MSI_IRQ + raw_spinlock_t msi_lock; struct list_head msi_list; #endif -- cgit v1.2.3