[Xen-devel] [PATCH] Bypass mask bit of msix entry in xen

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>]

Currently xen doesn't support passthrough mask bit in msix entry,
this will conflict with qemu's control to that bit.
Pass it in xen and let device module simulate it.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
---
 xen/arch/x86/hvm/vmsi.c |   67 +++++++++++-----------------------------------
 1 files changed, 16 insertions(+), 51 deletions(-)

diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
index cfc7c80..845cf4c 100644
--- a/xen/arch/x86/hvm/vmsi.c
+++ b/xen/arch/x86/hvm/vmsi.c
@@ -167,7 +167,7 @@ struct msixtbl_entry
     unsigned long table_flags[BITS_TO_LONGS(MAX_MSIX_TABLE_ENTRIES)];
 #define MAX_MSIX_ACC_ENTRIES 3
     struct { 
-        uint32_t msi_ad[3];    /* Shadow of address low, high and data */
+        uint32_t msi_ad[4];    /* Shadow of address low, high, data and 
control */
     } gentries[MAX_MSIX_ACC_ENTRIES];
     struct rcu_head rcu;
 };
@@ -213,7 +213,6 @@ static int msixtbl_read(
 {
     unsigned long offset;
     struct msixtbl_entry *entry;
-    void *virt;
     unsigned int nr_entry, index;
     int r = X86EMUL_UNHANDLEABLE;
 
@@ -224,23 +223,14 @@ static int msixtbl_read(
 
     entry = msixtbl_find_entry(v, address);
     offset = address & (PCI_MSIX_ENTRY_SIZE - 1);
+    nr_entry = (address - entry->gtable) / PCI_MSIX_ENTRY_SIZE;
+
+    if ( nr_entry >= MAX_MSIX_ACC_ENTRIES )
+        goto out;
+
+    index = offset / sizeof(uint32_t);
+    *pval = entry->gentries[nr_entry].msi_ad[index];
 
-    if ( offset != PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET )
-    {
-        nr_entry = (address - entry->gtable) / PCI_MSIX_ENTRY_SIZE;
-        if ( nr_entry >= MAX_MSIX_ACC_ENTRIES )
-            goto out;
-        index = offset / sizeof(uint32_t);
-        *pval = entry->gentries[nr_entry].msi_ad[index];
-    }
-    else 
-    {
-        virt = msixtbl_addr_to_virt(entry, address);
-        if ( !virt )
-            goto out;
-        *pval = readl(virt);
-    }
-    
     r = X86EMUL_OKAY;
 out:
     rcu_read_unlock(&msixtbl_rcu_lock);
@@ -252,7 +242,6 @@ static int msixtbl_write(struct vcpu *v, unsigned long 
address,
 {
     unsigned long offset;
     struct msixtbl_entry *entry;
-    void *virt;
     unsigned int nr_entry, index;
     int r = X86EMUL_UNHANDLEABLE;
 
@@ -264,42 +253,18 @@ static int msixtbl_write(struct vcpu *v, unsigned long 
address,
     entry = msixtbl_find_entry(v, address);
     nr_entry = (address - entry->gtable) / PCI_MSIX_ENTRY_SIZE;
 
-    offset = address & (PCI_MSIX_ENTRY_SIZE - 1);
-    if ( offset != PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET)
-    {
-        if ( nr_entry < MAX_MSIX_ACC_ENTRIES ) 
-        {
-            index = offset / sizeof(uint32_t);
-            entry->gentries[nr_entry].msi_ad[index] = val;
-        }
-        set_bit(nr_entry, &entry->table_flags);
-        goto out;
-    }
-
-    /* exit to device model if address/data has been modified */
-    if ( test_and_clear_bit(nr_entry, &entry->table_flags) )
+    if ( nr_entry >= MAX_MSIX_ACC_ENTRIES )
         goto out;
 
-    virt = msixtbl_addr_to_virt(entry, address);
-    if ( !virt )
-        goto out;
+    offset = address & (PCI_MSIX_ENTRY_SIZE - 1);
+    index = offset / sizeof(uint32_t);
+    entry->gentries[nr_entry].msi_ad[index] = val;
 
-    /* Do not allow the mask bit to be changed. */
-#if 0 /* XXX
-       * As the mask bit is the only defined bit in the word, and as the
-       * host MSI-X code doesn't preserve the other bits anyway, doing
-       * this is pointless. So for now just discard the write (also
-       * saving us from having to determine the matching irq_desc).
-       */
-    spin_lock_irqsave(&desc->lock, flags);
-    orig = readl(virt);
-    val &= ~PCI_MSIX_VECTOR_BITMASK;
-    val |= orig & PCI_MSIX_VECTOR_BITMASK;
-    writel(val, virt);
-    spin_unlock_irqrestore(&desc->lock, flags);
-#endif
+    if ( offset != PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET)
+        set_bit(nr_entry, &entry->table_flags);
+    else
+        clear_bit(nr_entry, &entry->table_flags);
 
-    r = X86EMUL_OKAY;
 out:
     rcu_read_unlock(&msixtbl_rcu_lock);
     return r;
-- 
1.7.3


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