[v2,04/10] AMD/IOMMU: use bit field for IRTE
diff mbox series

Message ID 5D14DECD020000780023B984@prv1-mh.provo.novell.com
State New, archived
Headers show
Series
  • x86: AMD x2APIC support
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Commit Message

Jan Beulich June 27, 2019, 3:20 p.m. UTC
At the same time restrict its scope to just the single source file
actually using it, and abstract accesses by introducing a union of
pointers. (A union of the actual table entries is not used to make it
impossible to [wrongly, once the 128-bit form gets added] perform
pointer arithmetic / array accesses on derived types.)

Also move away from updating the entries piecemeal: Construct a full new
entry, and write it out.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: name {get,free}_intremap_entry()'s last parameter "index" instead of
    "offset". Introduce union irte32.
---
It would have been nice to use write_atomic() or ACCESS_ONCE() for the
actual writes, but both cast the value to a scalar one, which doesn't
suit us here (and I also didn't want to make the compound type a union
with a raw member just for this).

Comments

Andrew Cooper July 2, 2019, 12:33 p.m. UTC | #1
On 27/06/2019 16:20, Jan Beulich wrote:
> At the same time restrict its scope to just the single source file
> actually using it, and abstract accesses by introducing a union of
> pointers. (A union of the actual table entries is not used to make it
> impossible to [wrongly, once the 128-bit form gets added] perform
> pointer arithmetic / array accesses on derived types.)
>
> Also move away from updating the entries piecemeal: Construct a full new
> entry, and write it out.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2: name {get,free}_intremap_entry()'s last parameter "index" instead of
>     "offset". Introduce union irte32.
> ---
> It would have been nice to use write_atomic() or ACCESS_ONCE() for the
> actual writes, but both cast the value to a scalar one, which doesn't
> suit us here (and I also didn't want to make the compound type a union
> with a raw member just for this).

This comment is stale.  However, I'm still confused as to what the
problem with putting a raw in union irte_basic is.

In particular, the containerof() usage is complicated to follow, and I
don't see it as being necessary.

~Andrew
Jan Beulich July 2, 2019, 1:56 p.m. UTC | #2
On 02.07.2019 14:33, Andrew Cooper wrote:
> On 27/06/2019 16:20, Jan Beulich wrote:
>> At the same time restrict its scope to just the single source file
>> actually using it, and abstract accesses by introducing a union of
>> pointers. (A union of the actual table entries is not used to make it
>> impossible to [wrongly, once the 128-bit form gets added] perform
>> pointer arithmetic / array accesses on derived types.)
>>
>> Also move away from updating the entries piecemeal: Construct a full new
>> entry, and write it out.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>> ---
>> v2: name {get,free}_intremap_entry()'s last parameter "index" instead of
>>      "offset". Introduce union irte32.
>> ---
>> It would have been nice to use write_atomic() or ACCESS_ONCE() for the
>> actual writes, but both cast the value to a scalar one, which doesn't
>> suit us here (and I also didn't want to make the compound type a union
>> with a raw member just for this).
> 
> This comment is stale.  However, I'm still confused as to what the
> problem with putting a raw in union irte_basic is.

That'll again require an intermediate "flds" (or however we choose to
name it) union field name for the bitfield structure, or else once
again initializers won't work with old gcc.

> In particular, the containerof() usage is complicated to follow, and I
> don't see it as being necessary.

Well, I can drop it if we're happy about the extra intermediate field
name (personally I'm not, but I'd accept it if it's considered less bad
than the containerof() approach).

Jan

Patch
diff mbox series

--- a/xen/drivers/passthrough/amd/iommu_intr.c
+++ b/xen/drivers/passthrough/amd/iommu_intr.c
@@ -23,6 +23,28 @@ 
 #include <asm/io_apic.h>
 #include <xen/keyhandler.h>
 
+struct irte_basic {
+    unsigned int remap_en:1;
+    unsigned int sup_io_pf:1;
+    unsigned int int_type:3;
+    unsigned int rq_eoi:1;
+    unsigned int dm:1;
+    unsigned int guest_mode:1; /* MBZ */
+    unsigned int dest:8;
+    unsigned int vector:8;
+    unsigned int :8;
+};
+
+union irte32 {
+    uint32_t raw[1];
+    struct irte_basic basic;
+};
+
+union irte_ptr {
+    void *ptr;
+    union irte32 *ptr32;
+};
+
 #define INTREMAP_TABLE_ORDER    1
 #define INTREMAP_LENGTH 0xB
 #define INTREMAP_ENTRIES (1 << INTREMAP_LENGTH)
@@ -101,47 +123,46 @@  static unsigned int alloc_intremap_entry
     return slot;
 }
 
-static u32 *get_intremap_entry(int seg, int bdf, int offset)
+static union irte_ptr get_intremap_entry(unsigned int seg, unsigned int bdf,
+                                         unsigned int index)
 {
-    u32 *table = get_ivrs_mappings(seg)[bdf].intremap_table;
+    union irte_ptr table = {
+        .ptr = get_ivrs_mappings(seg)[bdf].intremap_table
+    };
+
+    ASSERT(table.ptr && (index < INTREMAP_ENTRIES));
 
-    ASSERT( (table != NULL) && (offset < INTREMAP_ENTRIES) );
+    table.ptr32 += index;
 
-    return table + offset;
+    return table;
 }
 
-static void free_intremap_entry(int seg, int bdf, int offset)
-{
-    u32 *entry = get_intremap_entry(seg, bdf, offset);
-
-    memset(entry, 0, sizeof(u32));
-    __clear_bit(offset, get_ivrs_mappings(seg)[bdf].intremap_inuse);
-}
-
-static void update_intremap_entry(u32* entry, u8 vector, u8 int_type,
-    u8 dest_mode, u8 dest)
-{
-    set_field_in_reg_u32(IOMMU_CONTROL_ENABLED, 0,
-                            INT_REMAP_ENTRY_REMAPEN_MASK,
-                            INT_REMAP_ENTRY_REMAPEN_SHIFT, entry);
-    set_field_in_reg_u32(IOMMU_CONTROL_DISABLED, *entry,
-                            INT_REMAP_ENTRY_SUPIOPF_MASK,
-                            INT_REMAP_ENTRY_SUPIOPF_SHIFT, entry);
-    set_field_in_reg_u32(int_type, *entry,
-                            INT_REMAP_ENTRY_INTTYPE_MASK,
-                            INT_REMAP_ENTRY_INTTYPE_SHIFT, entry);
-    set_field_in_reg_u32(IOMMU_CONTROL_DISABLED, *entry,
-                            INT_REMAP_ENTRY_REQEOI_MASK,
-                            INT_REMAP_ENTRY_REQEOI_SHIFT, entry);
-    set_field_in_reg_u32((u32)dest_mode, *entry,
-                            INT_REMAP_ENTRY_DM_MASK,
-                            INT_REMAP_ENTRY_DM_SHIFT, entry);
-    set_field_in_reg_u32((u32)dest, *entry,
-                            INT_REMAP_ENTRY_DEST_MAST,
-                            INT_REMAP_ENTRY_DEST_SHIFT, entry);
-    set_field_in_reg_u32((u32)vector, *entry,
-                            INT_REMAP_ENTRY_VECTOR_MASK,
-                            INT_REMAP_ENTRY_VECTOR_SHIFT, entry);
+static void free_intremap_entry(unsigned int seg, unsigned int bdf,
+                                unsigned int index)
+{
+    union irte_ptr entry = get_intremap_entry(seg, bdf, index);
+
+    ACCESS_ONCE(entry.ptr32->raw[0]) = 0;
+
+    __clear_bit(index, get_ivrs_mappings(seg)[bdf].intremap_inuse);
+}
+
+static void update_intremap_entry(union irte_ptr entry, unsigned int vector,
+                                  unsigned int int_type,
+                                  unsigned int dest_mode, unsigned int dest)
+{
+    struct irte_basic basic = {
+        .remap_en = 1,
+        .sup_io_pf = 0,
+        .int_type = int_type,
+        .rq_eoi = 0,
+        .dm = dest_mode,
+        .dest = dest,
+        .vector = vector,
+    };
+
+    ACCESS_ONCE(entry.ptr32->raw[0]) =
+        container_of(&basic, union irte32, basic)->raw[0];
 }
 
 static inline int get_rte_index(const struct IO_APIC_route_entry *rte)
@@ -163,7 +184,7 @@  static int update_intremap_entry_from_io
     u16 *index)
 {
     unsigned long flags;
-    u32* entry;
+    union irte_ptr entry;
     u8 delivery_mode, dest, vector, dest_mode;
     int req_id;
     spinlock_t *lock;
@@ -201,12 +222,8 @@  static int update_intremap_entry_from_io
          * so need to recover vector and delivery mode from IRTE.
          */
         ASSERT(get_rte_index(rte) == offset);
-        vector = get_field_from_reg_u32(*entry,
-                                        INT_REMAP_ENTRY_VECTOR_MASK,
-                                        INT_REMAP_ENTRY_VECTOR_SHIFT);
-        delivery_mode = get_field_from_reg_u32(*entry,
-                                               INT_REMAP_ENTRY_INTTYPE_MASK,
-                                               INT_REMAP_ENTRY_INTTYPE_SHIFT);
+        vector = entry.ptr32->basic.vector;
+        delivery_mode = entry.ptr32->basic.int_type;
     }
     update_intremap_entry(entry, vector, delivery_mode, dest_mode, dest);
 
@@ -228,7 +245,7 @@  int __init amd_iommu_setup_ioapic_remapp
 {
     struct IO_APIC_route_entry rte;
     unsigned long flags;
-    u32* entry;
+    union irte_ptr entry;
     int apic, pin;
     u8 delivery_mode, dest, vector, dest_mode;
     u16 seg, bdf, req_id;
@@ -407,16 +424,14 @@  unsigned int amd_iommu_read_ioapic_from_
         u16 bdf = ioapic_sbdf[idx].bdf;
         u16 seg = ioapic_sbdf[idx].seg;
         u16 req_id = get_intremap_requestor_id(seg, bdf);
-        const u32 *entry = get_intremap_entry(seg, req_id, offset);
+        union irte_ptr entry = get_intremap_entry(seg, req_id, offset);
 
         ASSERT(offset == (val & (INTREMAP_ENTRIES - 1)));
         val &= ~(INTREMAP_ENTRIES - 1);
-        val |= get_field_from_reg_u32(*entry,
-                                      INT_REMAP_ENTRY_INTTYPE_MASK,
-                                      INT_REMAP_ENTRY_INTTYPE_SHIFT) << 8;
-        val |= get_field_from_reg_u32(*entry,
-                                      INT_REMAP_ENTRY_VECTOR_MASK,
-                                      INT_REMAP_ENTRY_VECTOR_SHIFT);
+        val |= MASK_INSR(entry.ptr32->basic.int_type,
+                         IO_APIC_REDIR_DELIV_MODE_MASK);
+        val |= MASK_INSR(entry.ptr32->basic.vector,
+                         IO_APIC_REDIR_VECTOR_MASK);
     }
 
     return val;
@@ -427,7 +442,7 @@  static int update_intremap_entry_from_ms
     int *remap_index, const struct msi_msg *msg, u32 *data)
 {
     unsigned long flags;
-    u32* entry;
+    union irte_ptr entry;
     u16 req_id, alias_id;
     u8 delivery_mode, dest, vector, dest_mode;
     spinlock_t *lock;
@@ -581,7 +596,7 @@  void amd_iommu_read_msi_from_ire(
     const struct pci_dev *pdev = msi_desc->dev;
     u16 bdf = pdev ? PCI_BDF2(pdev->bus, pdev->devfn) : hpet_sbdf.bdf;
     u16 seg = pdev ? pdev->seg : hpet_sbdf.seg;
-    const u32 *entry;
+    union irte_ptr entry;
 
     if ( IS_ERR_OR_NULL(_find_iommu_for_device(seg, bdf)) )
         return;
@@ -597,12 +612,10 @@  void amd_iommu_read_msi_from_ire(
     }
 
     msg->data &= ~(INTREMAP_ENTRIES - 1);
-    msg->data |= get_field_from_reg_u32(*entry,
-                                        INT_REMAP_ENTRY_INTTYPE_MASK,
-                                        INT_REMAP_ENTRY_INTTYPE_SHIFT) << 8;
-    msg->data |= get_field_from_reg_u32(*entry,
-                                        INT_REMAP_ENTRY_VECTOR_MASK,
-                                        INT_REMAP_ENTRY_VECTOR_SHIFT);
+    msg->data |= MASK_INSR(entry.ptr32->basic.int_type,
+                           MSI_DATA_DELIVERY_MODE_MASK);
+    msg->data |= MASK_INSR(entry.ptr32->basic.vector,
+                           MSI_DATA_VECTOR_MASK);
 }
 
 int __init amd_iommu_free_intremap_table(
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
@@ -469,22 +469,6 @@  struct amd_iommu_pte {
 #define IOMMU_CONTROL_DISABLED	0
 #define IOMMU_CONTROL_ENABLED	1
 
-/* interrupt remapping table */
-#define INT_REMAP_ENTRY_REMAPEN_MASK    0x00000001
-#define INT_REMAP_ENTRY_REMAPEN_SHIFT   0
-#define INT_REMAP_ENTRY_SUPIOPF_MASK    0x00000002
-#define INT_REMAP_ENTRY_SUPIOPF_SHIFT   1
-#define INT_REMAP_ENTRY_INTTYPE_MASK    0x0000001C
-#define INT_REMAP_ENTRY_INTTYPE_SHIFT   2
-#define INT_REMAP_ENTRY_REQEOI_MASK     0x00000020
-#define INT_REMAP_ENTRY_REQEOI_SHIFT    5
-#define INT_REMAP_ENTRY_DM_MASK         0x00000040
-#define INT_REMAP_ENTRY_DM_SHIFT        6
-#define INT_REMAP_ENTRY_DEST_MAST       0x0000FF00
-#define INT_REMAP_ENTRY_DEST_SHIFT      8
-#define INT_REMAP_ENTRY_VECTOR_MASK     0x00FF0000
-#define INT_REMAP_ENTRY_VECTOR_SHIFT    16
-
 #define INV_IOMMU_ALL_PAGES_ADDRESS      ((1ULL << 63) - 1)
 
 #define IOMMU_RING_BUFFER_PTR_MASK                  0x0007FFF0