From 7307e1523ae7deb9ea206a75a23ecc8e60524575 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 10 Jun 2015 14:17:45 +0100 Subject: [PATCH] xen/MSI: don't open-code pass-through of enable bit modifications Without this the actual XSA-131 fix would cause the enable bit to not get set anymore (due to the write back getting suppressed there based on the OR of emu_mask, ro_mask, and res_mask). Note that the fiddling with the enable bit shouldn't really be done by qemu, but making this work right (via libxc and the hypervisor) will require more extensive changes, which can be postponed until after the security issue got addressed. This is a preparatory patch for XSA-131. Signed-off-by: Jan Beulich Acked-by: Stefano Stabellini --- hw/pass-through.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/hw/pass-through.c b/hw/pass-through.c index 2e210a347..81a8de2bb 100644 --- a/hw/pass-through.c +++ b/hw/pass-through.c @@ -648,7 +648,7 @@ static struct pt_reg_info_tbl pt_emu_reg_msi_tbl[] = { .size = 2, .init_val = 0x0000, .ro_mask = 0xFF8E, - .emu_mask = 0x017F, + .emu_mask = 0x017E, .init = pt_msgctrl_reg_init, .u.w.read = pt_word_reg_read, .u.w.write = pt_msgctrl_reg_write, @@ -3899,6 +3899,9 @@ static int pt_msgctrl_reg_write(struct pt_dev *ptdev, /* modify emulate register */ writable_mask = reg->emu_mask & ~reg->ro_mask & valid_mask; + /* also emulate MSI_ENABLE bit for MSI-INTx translation */ + if (ptdev->msi_trans_en) + writable_mask |= PCI_MSI_FLAGS_ENABLE & valid_mask; cfg_entry->data = PT_MERGE_VALUE(*value, cfg_entry->data, writable_mask); /* update the msi_info too */ ptdev->msi->flags |= cfg_entry->data & @@ -3907,6 +3910,9 @@ static int pt_msgctrl_reg_write(struct pt_dev *ptdev, /* create value for writing to I/O device register */ val = *value; throughable_mask = ~reg->emu_mask & valid_mask; + /* don't pass through MSI_ENABLE bit for MSI-INTx translation */ + if (ptdev->msi_trans_en) + throughable_mask &= ~PCI_MSI_FLAGS_ENABLE; *value = PT_MERGE_VALUE(*value, dev_value, throughable_mask); /* update MSI */ @@ -3946,12 +3952,6 @@ static int pt_msgctrl_reg_write(struct pt_dev *ptdev, else ptdev->msi->flags &= ~PCI_MSI_FLAGS_ENABLE; - /* pass through MSI_ENABLE bit when no MSI-INTx translation */ - if (!ptdev->msi_trans_en) { - *value &= ~PCI_MSI_FLAGS_ENABLE; - *value |= val & PCI_MSI_FLAGS_ENABLE; - } - return 0; } -- 2.39.5