[Xen-changelog] [qemu-xen-4.2-testing] xen/MSI: don't open-code pass-through of enable bit modifications

[patchbot@xxxxxxx]

commit 7307e1523ae7deb9ea206a75a23ecc8e60524575
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Jun 10 14:17:45 2015 +0100
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Wed Jun 10 14:17:45 2015 +0100

    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 <jbeulich@xxxxxxxx>
    Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 hw/pass-through.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/hw/pass-through.c b/hw/pass-through.c
index 2e210a3..81a8de2 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;
 }
 
--
generated by git-patchbot for /home/xen/git/qemu-xen-4.2-testing.git

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