From a46126fec20e0cf4f5442352ef45efaea8c89646 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 12 Oct 2017 14:36:58 +0200 Subject: [PATCH] x86/MSI: disallow redundant enabling At the moment, Xen attempts to allow redundant enabling of MSI by having pci_enable_msi() return 0, and point to the existing MSI descriptor, when the msi already exists. Unfortunately, if subsequent errors are encountered, the cleanup paths assume pci_enable_msi() had done full initialization, and hence undo everything that was assumed to be done by that function without also undoing other setup that would normally occur only after that function was called (in map_domain_pirq() itself). Rather than try to make the redundant enabling case work properly, just forbid it entirely by having pci_enable_msi() return -EEXIST when MSI is already set up. This is part of XSA-237. Reported-by: HW42 Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper Reviewed-by: George Dunlap --- xen/arch/x86/msi.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c index 77998f4fb3..4652b98c2d 100644 --- a/xen/arch/x86/msi.c +++ b/xen/arch/x86/msi.c @@ -1050,11 +1050,10 @@ static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc) old_desc = find_msi_entry(pdev, msi->irq, PCI_CAP_ID_MSI); if ( old_desc ) { - printk(XENLOG_WARNING "irq %d already mapped to MSI on %04x:%02x:%02x.%u\n", + printk(XENLOG_ERR "irq %d already mapped to MSI on %04x:%02x:%02x.%u\n", msi->irq, msi->seg, msi->bus, PCI_SLOT(msi->devfn), PCI_FUNC(msi->devfn)); - *desc = old_desc; - return 0; + return -EEXIST; } old_desc = find_msi_entry(pdev, -1, PCI_CAP_ID_MSIX); @@ -1118,11 +1117,10 @@ static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc) old_desc = find_msi_entry(pdev, msi->irq, PCI_CAP_ID_MSIX); if ( old_desc ) { - printk(XENLOG_WARNING "irq %d already mapped to MSI-X on %04x:%02x:%02x.%u\n", + printk(XENLOG_ERR "irq %d already mapped to MSI-X on %04x:%02x:%02x.%u\n", msi->irq, msi->seg, msi->bus, PCI_SLOT(msi->devfn), PCI_FUNC(msi->devfn)); - *desc = old_desc; - return 0; + return -EEXIST; } old_desc = find_msi_entry(pdev, -1, PCI_CAP_ID_MSI); -- 2.30.2