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[PATCH] x86/msi: dynamically map pages for MSI-X tables



Xen reserves a constant number of pages that can be used for mapping
MSI-X tables. This limit is defined by FIX_MSIX_MAX_PAGES in fixmap.h.

Reserving a fixed number of pages could result in an -ENOMEM if a
device requests a new page when the fixmap limit is exhausted and will
necessitate manually adjusting the limit before compilation.

To avoid the issues with the current fixmap implementation, we modify
the MSI-X page mapping logic to instead dynamically map new pages when
they are needed by making use of ioremap().

Signed-off-by: Ruben Hakobyan <hakor@xxxxxxxxxx>
---
 xen/arch/x86/include/asm/fixmap.h |  2 -
 xen/arch/x86/include/asm/msi.h    |  5 +--
 xen/arch/x86/msi.c                | 69 ++++++++-----------------------
 3 files changed, 19 insertions(+), 57 deletions(-)

diff --git a/xen/arch/x86/include/asm/fixmap.h 
b/xen/arch/x86/include/asm/fixmap.h
index 516ec3fa6c..139c3e2dcc 100644
--- a/xen/arch/x86/include/asm/fixmap.h
+++ b/xen/arch/x86/include/asm/fixmap.h
@@ -61,8 +61,6 @@ enum fixed_addresses {
     FIX_ACPI_END = FIX_ACPI_BEGIN + NUM_FIXMAP_ACPI_PAGES - 1,
     FIX_HPET_BASE,
     FIX_TBOOT_SHARED_BASE,
-    FIX_MSIX_IO_RESERV_BASE,
-    FIX_MSIX_IO_RESERV_END = FIX_MSIX_IO_RESERV_BASE + FIX_MSIX_MAX_PAGES -1,
     FIX_TBOOT_MAP_ADDRESS,
     FIX_APEI_RANGE_BASE,
     FIX_APEI_RANGE_END = FIX_APEI_RANGE_BASE + FIX_APEI_RANGE_MAX -1,
diff --git a/xen/arch/x86/include/asm/msi.h b/xen/arch/x86/include/asm/msi.h
index a53ade95c9..16c80c9883 100644
--- a/xen/arch/x86/include/asm/msi.h
+++ b/xen/arch/x86/include/asm/msi.h
@@ -55,9 +55,6 @@
 #define         MSI_ADDR_DEST_ID_MASK          0x00ff000
 #define  MSI_ADDR_DEST_ID(dest)                (((dest) << 
MSI_ADDR_DEST_ID_SHIFT) & MSI_ADDR_DEST_ID_MASK)
 
-/* MAX fixed pages reserved for mapping MSIX tables. */
-#define FIX_MSIX_MAX_PAGES              512
-
 struct msi_info {
     pci_sbdf_t sbdf;
     int irq;
@@ -213,7 +210,7 @@ struct arch_msix {
         unsigned long first, last;
     } table, pba;
     int table_refcnt[MAX_MSIX_TABLE_PAGES];
-    int table_idx[MAX_MSIX_TABLE_PAGES];
+    void __iomem *table_va[MAX_MSIX_TABLE_PAGES];
     spinlock_t table_lock;
     bool host_maskall, guest_maskall;
     domid_t warned;
diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index d0bf63df1d..8128274c07 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -24,7 +24,6 @@
 #include <asm/smp.h>
 #include <asm/desc.h>
 #include <asm/msi.h>
-#include <asm/fixmap.h>
 #include <asm/p2m.h>
 #include <mach_apic.h>
 #include <io_ports.h>
@@ -39,75 +38,44 @@ boolean_param("msi", use_msi);
 
 static void __pci_disable_msix(struct msi_desc *);
 
-/* bitmap indicate which fixed map is free */
-static DEFINE_SPINLOCK(msix_fixmap_lock);
-static DECLARE_BITMAP(msix_fixmap_pages, FIX_MSIX_MAX_PAGES);
-
-static int msix_fixmap_alloc(void)
-{
-    int i, rc = -ENOMEM;
-
-    spin_lock(&msix_fixmap_lock);
-    for ( i = 0; i < FIX_MSIX_MAX_PAGES; i++ )
-        if ( !test_bit(i, &msix_fixmap_pages) )
-            break;
-    if ( i == FIX_MSIX_MAX_PAGES )
-        goto out;
-    rc = FIX_MSIX_IO_RESERV_BASE + i;
-    set_bit(i, &msix_fixmap_pages);
-
- out:
-    spin_unlock(&msix_fixmap_lock);
-    return rc;
-}
-
-static void msix_fixmap_free(int idx)
-{
-    spin_lock(&msix_fixmap_lock);
-    if ( idx >= FIX_MSIX_IO_RESERV_BASE )
-        clear_bit(idx - FIX_MSIX_IO_RESERV_BASE, &msix_fixmap_pages);
-    spin_unlock(&msix_fixmap_lock);
-}
-
-static int msix_get_fixmap(struct arch_msix *msix, u64 table_paddr,
+static void __iomem *msix_map_table(struct arch_msix *msix, u64 table_paddr,
                            u64 entry_paddr)
 {
     long nr_page;
-    int idx;
+    void __iomem *va = NULL;
 
     nr_page = (entry_paddr >> PAGE_SHIFT) - (table_paddr >> PAGE_SHIFT);
 
     if ( nr_page < 0 || nr_page >= MAX_MSIX_TABLE_PAGES )
-        return -EINVAL;
+        return NULL;
 
     spin_lock(&msix->table_lock);
     if ( msix->table_refcnt[nr_page]++ == 0 )
     {
-        idx = msix_fixmap_alloc();
-        if ( idx < 0 )
+        va = ioremap(entry_paddr, PAGE_SIZE);
+        if ( va == NULL )
         {
             msix->table_refcnt[nr_page]--;
             goto out;
         }
-        set_fixmap_nocache(idx, entry_paddr);
-        msix->table_idx[nr_page] = idx;
+        msix->table_va[nr_page] = va;
     }
     else
-        idx = msix->table_idx[nr_page];
+        va = msix->table_va[nr_page];
 
  out:
     spin_unlock(&msix->table_lock);
-    return idx;
+    return va;
 }
 
-static void msix_put_fixmap(struct arch_msix *msix, int idx)
+static void msix_unmap_table(struct arch_msix *msix, void __iomem *va)
 {
     int i;
 
     spin_lock(&msix->table_lock);
     for ( i = 0; i < MAX_MSIX_TABLE_PAGES; i++ )
     {
-        if ( msix->table_idx[i] == idx )
+        if ( msix->table_va[i] == va )
             break;
     }
     if ( i == MAX_MSIX_TABLE_PAGES )
@@ -115,9 +83,8 @@ static void msix_put_fixmap(struct arch_msix *msix, int idx)
 
     if ( --msix->table_refcnt[i] == 0 )
     {
-        clear_fixmap(idx);
-        msix_fixmap_free(idx);
-        msix->table_idx[i] = 0;
+        vunmap(va);
+        msix->table_va[i] = NULL;
     }
 
  out:
@@ -568,8 +535,8 @@ int msi_free_irq(struct msi_desc *entry)
     }
 
     if ( entry->msi_attrib.type == PCI_CAP_ID_MSIX )
-        msix_put_fixmap(entry->dev->msix,
-                        virt_to_fix((unsigned long)entry->mask_base));
+        msix_unmap_table(entry->dev->msix,
+                       (void*)((unsigned long)entry->mask_base & PAGE_MASK));
 
     list_del(&entry->list);
     xfree(entry);
@@ -892,10 +859,10 @@ static int msix_capability_init(struct pci_dev *dev,
     {
         /* Map MSI-X table region */
         u64 entry_paddr = table_paddr + msi->entry_nr * PCI_MSIX_ENTRY_SIZE;
-        int idx = msix_get_fixmap(msix, table_paddr, entry_paddr);
+        void __iomem *va = msix_map_table(msix, table_paddr, entry_paddr);
         void __iomem *base;
 
-        if ( idx < 0 )
+        if ( va == NULL )
         {
             if ( zap_on_error )
             {
@@ -907,9 +874,9 @@ static int msix_capability_init(struct pci_dev *dev,
 
             pci_conf_write16(dev->sbdf, msix_control_reg(pos), control);
             xfree(entry);
-            return idx;
+            return -ENOMEM;
         }
-        base = fix_to_virt(idx) + (entry_paddr & (PAGE_SIZE - 1));
+        base = va + (entry_paddr & (PAGE_SIZE - 1));
 
         /* Mask interrupt here */
         writel(1, base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
-- 
2.39.2




 


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