[xen stable-4.13] x86/msi: get rid of read_msi_msg

[patchbot@xxxxxxx]

commit b7fcbe0150c7df1c0dc97853b46e1cf39f8d8ad9
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Tue Sep 22 16:22:08 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 22 16:22:08 2020 +0200

    x86/msi: get rid of read_msi_msg
    
    It's safer and faster to just use the cached last written
    (untranslated) MSI message stored in msi_desc for the single user that
    calls read_msi_msg.
    
    This also prevents relying on the data read from the device MSI
    registers in order to figure out the index into the IOMMU interrupt
    remapping table, which is not safe.
    
    This is part of XSA-337.
    
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/msi.c | 53 +----------------------------------------------------
 1 file changed, 1 insertion(+), 52 deletions(-)

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index 54d13aecf7..2d02f8aa86 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -183,54 +183,6 @@ void msi_compose_msg(unsigned vector, const cpumask_t 
*cpu_mask, struct msi_msg
                 MSI_DATA_VECTOR(vector);
 }
 
-static bool read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
-{
-    switch ( entry->msi_attrib.type )
-    {
-    case PCI_CAP_ID_MSI:
-    {
-        struct pci_dev *dev = entry->dev;
-        int pos = entry->msi_attrib.pos;
-        uint16_t data;
-
-        msg->address_lo = pci_conf_read32(dev->sbdf,
-                                          msi_lower_address_reg(pos));
-        if ( entry->msi_attrib.is_64 )
-        {
-            msg->address_hi = pci_conf_read32(dev->sbdf,
-                                              msi_upper_address_reg(pos));
-            data = pci_conf_read16(dev->sbdf, msi_data_reg(pos, 1));
-        }
-        else
-        {
-            msg->address_hi = 0;
-            data = pci_conf_read16(dev->sbdf, msi_data_reg(pos, 0));
-        }
-        msg->data = data;
-        break;
-    }
-    case PCI_CAP_ID_MSIX:
-    {
-        void __iomem *base = entry->mask_base;
-
-        if ( unlikely(!msix_memory_decoded(entry->dev,
-                                           entry->msi_attrib.pos)) )
-            return false;
-        msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR_OFFSET);
-        msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR_OFFSET);
-        msg->data = readl(base + PCI_MSIX_ENTRY_DATA_OFFSET);
-        break;
-    }
-    default:
-        BUG();
-    }
-
-    if ( iommu_intremap )
-        iommu_read_msi_from_ire(entry, msg);
-
-    return true;
-}
-
 static int write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
     entry->msg = *msg;
@@ -302,10 +254,7 @@ void set_msi_affinity(struct irq_desc *desc, const 
cpumask_t *mask)
 
     ASSERT(spin_is_locked(&desc->lock));
 
-    memset(&msg, 0, sizeof(msg));
-    if ( !read_msi_msg(msi_desc, &msg) )
-        return;
-
+    msg = msi_desc->msg;
     msg.data &= ~MSI_DATA_VECTOR_MASK;
     msg.data |= MSI_DATA_VECTOR(desc->arch.vector);
     msg.address_lo &= ~MSI_ADDR_DEST_ID_MASK;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.13