xen/io: provide helpers for multi size MMIO accesses

Several handlers have the same necessity of reading or writing from or to
an MMIO region using 1, 2, 4 or 8 bytes accesses.  So far this has been
open-coded in the function itself.  Instead provide a new set of handlers
that encapsulate the accesses.

Since the added helpers are not architecture specific, introduce a new
generic io.h header.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
index fd83abb929ec2e68f9d75826739cc5bcfcc6d5ff..61b89834d97d1078bee710f864bb5891b7b1632f 100644 (file)
--- a/xen/arch/x86/hvm/vmsi.c
+++ b/xen/arch/x86/hvm/vmsi.c
@@ -24,6 +24,7 @@
  * Will be merged it with virtual IOAPIC logic, since most is the same
 */
 
+#include <xen/io.h>
 #include <xen/types.h>
 #include <xen/mm.h>
 #include <xen/xmalloc.h>
@@ -304,28 +305,7 @@ static void adjacent_read(
 
     hwaddr = fix_to_virt(fixmap_idx) + PAGE_OFFSET(address);
 
-    switch ( len )
-    {
-    case 1:
-        *pval = readb(hwaddr);
-        break;
-
-    case 2:
-        *pval = readw(hwaddr);
-        break;
-
-    case 4:
-        *pval = readl(hwaddr);
-        break;
-
-    case 8:
-        *pval = readq(hwaddr);
-        break;
-
-    default:
-        ASSERT_UNREACHABLE();
-        break;
-    }
+    *pval = read_mmio(hwaddr, len);
 }
 
 static void adjacent_write(
@@ -344,28 +324,7 @@ static void adjacent_write(
 
     hwaddr = fix_to_virt(fixmap_idx) + PAGE_OFFSET(address);
 
-    switch ( len )
-    {
-    case 1:
-        writeb(val, hwaddr);
-        break;
-
-    case 2:
-        writew(val, hwaddr);
-        break;
-
-    case 4:
-        writel(val, hwaddr);
-        break;
-
-    case 8:
-        writeq(val, hwaddr);
-        break;
-
-    default:
-        ASSERT_UNREACHABLE();
-        break;
-    }
+    write_mmio(hwaddr, val, len);
 }
 
 static int cf_check msixtbl_read(

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index ac5b51d17acacda60901b5643f40a1d2267af4b2..732ca1366f33c9452b4334ff31b6ddc6b7e012c6 100644 (file)
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -95,6 +95,7 @@
 #include <xen/guest_access.h>
 #include <xen/hypercall.h>
 #include <xen/init.h>
+#include <xen/io.h>
 #include <xen/iocap.h>
 #include <xen/ioreq.h>
 #include <xen/irq.h>
@@ -116,7 +117,6 @@
 #include <asm/flushtlb.h>
 #include <asm/guest.h>
 #include <asm/idt.h>
-#include <asm/io.h>
 #include <asm/io_apic.h>
 #include <asm/ldt.h>
 #include <asm/mem_sharing.h>
@@ -5102,7 +5102,7 @@ static void __iomem *subpage_mmio_map_page(
 static void subpage_mmio_write_emulate(
     mfn_t mfn,
     unsigned int offset,
-    const void *data,
+    unsigned long data,
     unsigned int len)
 {
     struct subpage_ro_range *entry;
@@ -5131,26 +5131,8 @@ static void subpage_mmio_write_emulate(
         return;
     }
 
-    addr += offset;
-    switch ( len )
-    {
-    case 1:
-        writeb(*(const uint8_t*)data, addr);
-        break;
-    case 2:
-        writew(*(const uint16_t*)data, addr);
-        break;
-    case 4:
-        writel(*(const uint32_t*)data, addr);
-        break;
-    case 8:
-        writeq(*(const uint64_t*)data, addr);
-        break;
-    default:
-        /* mmio_ro_emulated_write() already validated the size */
-        ASSERT_UNREACHABLE();
+    if ( !write_mmio(addr + offset, data, len) )
         goto write_ignored;
-    }
 }
 
 #ifdef CONFIG_HVM
@@ -5185,6 +5167,7 @@ int cf_check mmio_ro_emulated_write(
     struct x86_emulate_ctxt *ctxt)
 {
     struct mmio_ro_emulate_ctxt *mmio_ro_ctxt = ctxt->data;
+    unsigned long data = 0;
 
     /* Only allow naturally-aligned stores at the original %cr2 address. */
     if ( ((bytes | offset) & (bytes - 1)) || !bytes ||
@@ -5195,9 +5178,12 @@ int cf_check mmio_ro_emulated_write(
         return X86EMUL_UNHANDLEABLE;
     }
 
-    if ( bytes <= 8 )
+    if ( bytes <= sizeof(data) )
+    {
+        memcpy(&data, p_data, bytes);
         subpage_mmio_write_emulate(mmio_ro_ctxt->mfn, PAGE_OFFSET(offset),
-                                   p_data, bytes);
+                                   data, bytes);
+    }
     else if ( subpage_mmio_find_page(mmio_ro_ctxt->mfn) )
         gprintk(XENLOG_WARNING,
                 "unsupported %u-byte write to R/O MMIO 0x%"PRI_mfn"%03lx\n",

diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c
index 3568f2a6518311633ee9d93c93bbb18c7e103944..74211301ba103b34fa3c1a570e1e489670118f6b 100644 (file)
--- a/xen/drivers/vpci/msix.c
+++ b/xen/drivers/vpci/msix.c
@@ -17,6 +17,7 @@
  * License along with this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <xen/io.h>
 #include <xen/sched.h>
 #include <xen/vpci.h>
 
@@ -338,28 +339,7 @@ static int adjacent_read(const struct domain *d, const struct vpci_msix *msix,
         return X86EMUL_OKAY;
     }
 
-    switch ( len )
-    {
-    case 1:
-        *data = readb(mem + PAGE_OFFSET(addr));
-        break;
-
-    case 2:
-        *data = readw(mem + PAGE_OFFSET(addr));
-        break;
-
-    case 4:
-        *data = readl(mem + PAGE_OFFSET(addr));
-        break;
-
-    case 8:
-        *data = readq(mem + PAGE_OFFSET(addr));
-        break;
-
-    default:
-        ASSERT_UNREACHABLE();
-        break;
-    }
+    *data = read_mmio(mem + PAGE_OFFSET(addr), len);
     spin_unlock(&vpci->lock);
 
     return X86EMUL_OKAY;
@@ -487,28 +467,7 @@ static int adjacent_write(const struct domain *d, const struct vpci_msix *msix,
         return X86EMUL_OKAY;
     }
 
-    switch ( len )
-    {
-    case 1:
-        writeb(data, mem + PAGE_OFFSET(addr));
-        break;
-
-    case 2:
-        writew(data, mem + PAGE_OFFSET(addr));
-        break;
-
-    case 4:
-        writel(data, mem + PAGE_OFFSET(addr));
-        break;
-
-    case 8:
-        writeq(data, mem + PAGE_OFFSET(addr));
-        break;
-
-    default:
-        ASSERT_UNREACHABLE();
-        break;
-    }
+    write_mmio(mem + PAGE_OFFSET(addr), data, len);
     spin_unlock(&vpci->lock);
 
     return X86EMUL_OKAY;

diff --git a/xen/include/xen/io.h b/xen/include/xen/io.h
new file mode 100644 (file)
index 0000000..164a20c
--- /dev/null
+++ b/xen/include/xen/io.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * IO related routines.
+ *
+ * Copyright (c) 2025 Cloud Software Group
+ */
+#ifndef XEN_IO_H
+#define XEN_IO_H
+
+#include <xen/bug.h>
+
+#include <asm/io.h>
+
+static inline unsigned long read_mmio(const volatile void __iomem *mem,
+                                      unsigned int size)
+{
+    switch ( size )
+    {
+    case 1:
+        return readb(mem);
+
+    case 2:
+        return readw(mem);
+
+    case 4:
+        return readl(mem);
+
+#ifdef CONFIG_64BIT
+    case 8:
+        return readq(mem);
+#endif
+
+    default:
+        ASSERT_UNREACHABLE();
+        return ~0UL;
+    }
+}
+
+static inline bool write_mmio(volatile void __iomem *mem, unsigned long data,
+                              unsigned int size)
+{
+    switch ( size )
+    {
+    case 1:
+        writeb(data, mem);
+        break;
+
+    case 2:
+        writew(data, mem);
+        break;
+
+    case 4:
+        writel(data, mem);
+        break;
+
+#ifdef CONFIG_64BIT
+    case 8:
+        writeq(data, mem);
+        break;
+#endif
+
+    default:
+        ASSERT_UNREACHABLE();
+        return false;
+    }
+
+    return true;
+}
+
+#endif /* XEN_IO_H */