From 17323e8b689a1f6d1b711df034e9ee3a88ff27ba Mon Sep 17 00:00:00 2001 From: Dongli Zhang Date: Mon, 17 Dec 2018 07:34:39 +0800 Subject: [PATCH] msix: make pba size math more uniform In msix_exclusive_bar the bar_pba_size is more than what the pba is expected to have, although this never affects the bar size. Specifically, the math in msix_init_exclusive_bar allocates too much memory in some cases. For example consider nentries = 8. msix_exclusive_bar will give us bar_pba_size = 16. So 16 bytes. However 8 bytes would be enough - this is all that the spec requires. So in practice bar_pba_size sometimes allocates an extra 8 bytes but never more. Since each MSIX entry size is 16 bytes, and since we make sure that table+pba is a power of two, this always leaves a multiple of 16 bytes for the PBA, so extra 8 bytes have no effect. However, its ugly to have pba size temporary variable have an incorrect value. For consistency switch to the formula used in msix_init. Signed-off-by: Dongli Zhang Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/pci/msix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/pci/msix.c b/hw/pci/msix.c index c7bdbeda9e..4e336416a7 100644 --- a/hw/pci/msix.c +++ b/hw/pci/msix.c @@ -345,7 +345,7 @@ int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries, char *name; uint32_t bar_size = 4096; uint32_t bar_pba_offset = bar_size / 2; - uint32_t bar_pba_size = (nentries / 8 + 1) * 8; + uint32_t bar_pba_size = QEMU_ALIGN_UP(nentries, 64) / 8; /* * Migration compatibility dictates that this remains a 4k -- 2.11.4.GIT