[XEN v8 1/5] xen/arm: p2m: Use the pa_range_info table to support ARM_32 and ARM_64

[Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>]

Restructure the code so that one can use pa_range_info[] table for both
ARM_32 as well as ARM_64.

Also, removed the hardcoding for P2M_ROOT_ORDER and P2M_ROOT_LEVEL as
p2m_root_order can be obtained from the pa_range_info[].root_order and
p2m_root_level can be obtained from pa_range_info[].sl0.

Refer ARM DDI 0406C.d ID040418, B3-1345,
"Use of concatenated first-level translation tables

...However, a 40-bit input address range with a translation granularity of 4KB
requires a total of 28 bits of address resolution. Therefore, a stage 2
translation that supports a 40-bit input address range requires two concatenated
first-level translation tables,..."

Thus, root-order is 1 for 40-bit IPA on ARM_32.

Refer ARM DDI 0406C.d ID040418, B3-1348,

"Determining the required first lookup level for stage 2 translations

For a stage 2 translation, the output address range from the stage 1
translations determines the required input address range for the stage 2
translation. The permitted values of VTCR.SL0 are:

0b00 Stage 2 translation lookup must start at the second level.
0b01 Stage 2 translation lookup must start at the first level.

VTCR.T0SZ must indicate the required input address range. The size of the input
address region is 2^(32-T0SZ) bytes."

Thus VTCR.SL0 = 1 (maximum value) and VTCR.T0SZ = -8 when the size of input
address region is 2^40 bytes.

Thus, pa_range_info[].t0sz = 1 (VTCR.S) | 8 (VTCR.T0SZ) ie 11000b which is 24.

VTCR.T0SZ, is bits [5:0] for ARM_64.
VTCR.T0SZ is bits [3:0] and S(sign extension), bit[4] for ARM_32.

For this, we have used struct bitfields to convert pa_range_info[].t0sz to its
ARM_32 variant.

pa_range_info[] is indexed by ID_AA64MMFR0_EL1.PARange which is present in Arm64
only. This is the reason we do not specify the indices for ARM_32. Also, we
duplicated the entry "{ 40,      24/*24*/,  1,          1 }" between ARM_64 and
ARM_32. This is done to avoid introducing extra #if-defs.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
Changes from -

v3 - 1. New patch introduced in v4.
2. Restructure the code such that pa_range_info[] is used both by ARM_32 as
well as ARM_64.

v4 - 1. Removed the hardcoded definitions of P2M_ROOT_ORDER and P2M_ROOT_LEVEL.
The reason being root_order will not be always 1 (See the next patch).
2. Updated the commit message to explain t0sz, sl0 and root_order values for
32-bit IPA on Arm32.
3. Some sanity fixes.

v5 - pa_range_info is indexed by system_cpuinfo.mm64.pa_range. ie
when PARange is 0, the PA size is 32, 1 -> 36 and so on. So pa_range_info[] has
been updated accordingly.
For ARM_32 pa_range_info[0] = 0 and pa_range_info[1] = 0 as we do not support
32-bit, 36-bit physical address range yet.

v6 - 1. Added pa_range_info[] entries for ARM_32 without indices. Some entry
may be duplicated between ARM_64 and ARM_32.
2. Recalculate p2m_ipa_bits for ARM_32 from T0SZ (similar to ARM_64).
3. Introduced an union to reinterpret T0SZ bits between ARM_32 and ARM_64.

v7 - 1. Used struct bifield instead of union to reinterpret T0SZ bits between
ARM_32 and ARM_64.
2. Removed the invalid entry for ARM_32.

 xen/arch/arm/include/asm/p2m.h |  6 ----
 xen/arch/arm/p2m.c             | 50 +++++++++++++++++++++++++---------
 2 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/xen/arch/arm/include/asm/p2m.h b/xen/arch/arm/include/asm/p2m.h
index f67e9ddc72..940495d42b 100644
--- a/xen/arch/arm/include/asm/p2m.h
+++ b/xen/arch/arm/include/asm/p2m.h
@@ -14,16 +14,10 @@
 /* Holds the bit size of IPAs in p2m tables.  */
 extern unsigned int p2m_ipa_bits;
 
-#ifdef CONFIG_ARM_64
 extern unsigned int p2m_root_order;
 extern unsigned int p2m_root_level;
 #define P2M_ROOT_ORDER    p2m_root_order
 #define P2M_ROOT_LEVEL p2m_root_level
-#else
-/* First level P2M is always 2 consecutive pages */
-#define P2M_ROOT_ORDER    1
-#define P2M_ROOT_LEVEL 1
-#endif
 
 struct domain;
 
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 418997843d..76388ba54b 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -19,9 +19,9 @@
 
 #define INVALID_VMID 0 /* VMID 0 is reserved */
 
-#ifdef CONFIG_ARM_64
 unsigned int __read_mostly p2m_root_order;
 unsigned int __read_mostly p2m_root_level;
+#ifdef CONFIG_ARM_64
 static unsigned int __read_mostly max_vmid = MAX_VMID_8_BIT;
 /* VMID is by default 8 bit width on AArch64 */
 #define MAX_VMID       max_vmid
@@ -2247,16 +2247,6 @@ void __init setup_virt_paging(void)
     /* Setup Stage 2 address translation */
     register_t val = VTCR_RES1|VTCR_SH0_IS|VTCR_ORGN0_WBWA|VTCR_IRGN0_WBWA;
 
-#ifdef CONFIG_ARM_32
-    if ( p2m_ipa_bits < 40 )
-        panic("P2M: Not able to support %u-bit IPA at the moment\n",
-              p2m_ipa_bits);
-
-    printk("P2M: 40-bit IPA\n");
-    p2m_ipa_bits = 40;
-    val |= VTCR_T0SZ(0x18); /* 40 bit IPA */
-    val |= VTCR_SL0(0x1); /* P2M starts at first level */
-#else /* CONFIG_ARM_64 */
     static const struct {
         unsigned int pabits; /* Physical Address Size */
         unsigned int t0sz;   /* Desired T0SZ, minimum in comment */
@@ -2265,6 +2255,7 @@ void __init setup_virt_paging(void)
     } pa_range_info[] __initconst = {
         /* T0SZ minimum and SL0 maximum from ARM DDI 0487H.a Table D5-6 */
         /*      PA size, t0sz(min), root-order, sl0(max) */
+#ifdef CONFIG_ARM_64
         [0] = { 32,      32/*32*/,  0,          1 },
         [1] = { 36,      28/*28*/,  0,          1 },
         [2] = { 40,      24/*24*/,  1,          1 },
@@ -2273,11 +2264,28 @@ void __init setup_virt_paging(void)
         [5] = { 48,      16/*16*/,  0,          2 },
         [6] = { 52,      12/*12*/,  4,          2 },
         [7] = { 0 }  /* Invalid */
+#else
+        { 40,      24/*24*/,  1,          1 }
+#endif
     };
 
     unsigned int i;
     unsigned int pa_range = 0x10; /* Larger than any possible value */
 
+#ifdef CONFIG_ARM_32
+    /*
+     * Typecast pa_range_info[].t0sz into ARM_32 bit variant.
+     *
+     * VTCR.T0SZ is bits [3:0] and S(sign extension), bit[4] for ARM_32.
+     * Thus, pa_range_info[].t0sz is translated to its ARM_32 variant using
+     * struct bitfields.
+     */
+    struct
+    {
+        signed int val:5;
+    } t0sz_32;
+#else
+
     /*
      * Restrict "p2m_ipa_bits" if needed. As P2M table is always configured
      * with IPA bits == PA bits, compare against "pabits".
@@ -2291,6 +2299,7 @@ void __init setup_virt_paging(void)
      */
     if ( system_cpuinfo.mm64.vmid_bits == MM64_VMID_16_BITS_SUPPORT )
         max_vmid = MAX_VMID_16_BIT;
+#endif
 
     /* Choose suitable "pa_range" according to the resulted "p2m_ipa_bits". */
     for ( i = 0; i < ARRAY_SIZE(pa_range_info); i++ )
@@ -2304,26 +2313,41 @@ void __init setup_virt_paging(void)
 
     /* pa_range is 4 bits but we don't support all modes */
     if ( pa_range >= ARRAY_SIZE(pa_range_info) || 
!pa_range_info[pa_range].pabits )
-        panic("Unknown encoding of ID_AA64MMFR0_EL1.PARange %x\n", pa_range);
+    {
+        /*
+         * In case of ARM_64, we do not support this encoding of
+         * ID_AA64MMFR0_EL1.PARange
+         */
+        panic("Unsupported value for p2m_ipa_bits = 0x%x\n", p2m_ipa_bits);
+    }
 
+#ifdef CONFIG_ARM_64
     val |= VTCR_PS(pa_range);
     val |= VTCR_TG0_4K;
 
     /* Set the VS bit only if 16 bit VMID is supported. */
     if ( MAX_VMID == MAX_VMID_16_BIT )
         val |= VTCR_VS;
+#endif
+
     val |= VTCR_SL0(pa_range_info[pa_range].sl0);
     val |= VTCR_T0SZ(pa_range_info[pa_range].t0sz);
 
     p2m_root_order = pa_range_info[pa_range].root_order;
     p2m_root_level = 2 - pa_range_info[pa_range].sl0;
+
+#ifdef CONFIG_ARM_64
     p2m_ipa_bits = 64 - pa_range_info[pa_range].t0sz;
+#else
+    t0sz_32.val = pa_range_info[pa_range].t0sz;
+    p2m_ipa_bits = 32 - t0sz_32.val;
+#endif
 
     printk("P2M: %d-bit IPA with %d-bit PA and %d-bit VMID\n",
            p2m_ipa_bits,
            pa_range_info[pa_range].pabits,
            ( MAX_VMID == MAX_VMID_16_BIT ) ? 16 : 8);
-#endif
+
     printk("P2M: %d levels with order-%d root, VTCR 0x%"PRIregister"\n",
            4 - P2M_ROOT_LEVEL, P2M_ROOT_ORDER, val);
 
-- 
2.17.1