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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] xen/arm: guest_walk: Only generate necessary offsets/masks
commit 05031fa87357fad155f659cfc2dcce6614834684
Author: Julien Grall <jgrall@xxxxxxxxxx>
AuthorDate: Sun Apr 18 19:11:15 2021 +0100
Commit: Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Sun Apr 18 19:11:15 2021 +0100
xen/arm: guest_walk: Only generate necessary offsets/masks
At the moment, we are computing offsets/masks for each level and
granularity. This is a bit of waste given that we only need to
know the offsets/masks for the granularity used by the guest.
All the LPAE information can easily be inferred with just the
page shift for a given granularity and the level.
So rather than providing a set of helpers per granularity, we can
provide a single set that takes the granularity and the level in
parameters.
With the new helpers in place, we can rework guest_walk_ld() to
only compute necessary information.
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
Tested-by: Bertrand Marquish <bertrand.marquis@xxxxxxx>
---
xen/arch/arm/guest_walk.c | 37 ++-------------------
xen/include/asm-arm/lpae.h | 82 +++++++++++++++-------------------------------
2 files changed, 30 insertions(+), 89 deletions(-)
diff --git a/xen/arch/arm/guest_walk.c b/xen/arch/arm/guest_walk.c
index b4496c4c86..87de40d0cb 100644
--- a/xen/arch/arm/guest_walk.c
+++ b/xen/arch/arm/guest_walk.c
@@ -372,38 +372,6 @@ static bool guest_walk_ld(const struct vcpu *v,
register_t tcr = READ_SYSREG(TCR_EL1);
struct domain *d = v->domain;
-#define OFFSETS(gva, gran) \
-{ \
- zeroeth_table_offset_##gran(gva), \
- first_table_offset_##gran(gva), \
- second_table_offset_##gran(gva), \
- third_table_offset_##gran(gva) \
-}
-
- const paddr_t offsets[3][4] = {
- OFFSETS(gva, 4K),
- OFFSETS(gva, 16K),
- OFFSETS(gva, 64K)
- };
-
-#undef OFFSETS
-
-#define MASKS(gran) \
-{ \
- zeroeth_size(gran) - 1, \
- first_size(gran) - 1, \
- second_size(gran) - 1, \
- third_size(gran) - 1 \
-}
-
- static const paddr_t masks[3][4] = {
- MASKS(4K),
- MASKS(16K),
- MASKS(64K)
- };
-
-#undef MASKS
-
static const unsigned int grainsizes[3] = {
PAGE_SHIFT_4K,
PAGE_SHIFT_16K,
@@ -519,7 +487,7 @@ static bool guest_walk_ld(const struct vcpu *v,
* Add offset given by the GVA to the translation table base address.
* Shift the offset by 3 as it is 8-byte aligned.
*/
- paddr |= offsets[gran][level] << 3;
+ paddr |= LPAE_TABLE_INDEX_GS(grainsizes[gran], level, gva) << 3;
/* Access the guest's memory to read only one PTE. */
ret = access_guest_memory_by_ipa(d, paddr, &pte, sizeof(lpae_t),
false);
@@ -572,7 +540,8 @@ static bool guest_walk_ld(const struct vcpu *v,
/* Make sure that the lower bits of the PTE's base address are zero. */
mask = GENMASK_ULL(47, grainsizes[gran]);
- *ipa = (pfn_to_paddr(pte.walk.base) & mask) | (gva & masks[gran][level]);
+ *ipa = (pfn_to_paddr(pte.walk.base) & mask) |
+ (gva & (LEVEL_SIZE_GS(grainsizes[gran], level) - 1));
/*
* Set permissions so that the caller can check the flags by herself. Note
diff --git a/xen/include/asm-arm/lpae.h b/xen/include/asm-arm/lpae.h
index 4797f9cee4..e94de2e7d8 100644
--- a/xen/include/asm-arm/lpae.h
+++ b/xen/include/asm-arm/lpae.h
@@ -160,63 +160,35 @@ static inline bool lpae_is_superpage(lpae_t pte, unsigned
int level)
#define lpae_set_mfn(pte, mfn) ((pte).walk.base = mfn_x(mfn))
/*
- * AArch64 supports pages with different sizes (4K, 16K, and 64K). To enable
- * page table walks for various configurations, the following helpers enable
- * walking the translation table with varying page size granularities.
+ * AArch64 supports pages with different sizes (4K, 16K, and 64K).
+ * Provide a set of generic helpers that will compute various
+ * information based on the page granularity.
+ *
+ * Note the parameter 'gs' is the page shift of the granularity used.
+ * Some macro will evaluate 'gs' twice rather than storing in a
+ * variable. This is to allow using the macros in assembly.
+ */
+
+/*
+ * Granularity | PAGE_SHIFT | LPAE_SHIFT
+ * -------------------------------------
+ * 4K | 12 | 9
+ * 16K | 14 | 11
+ * 64K | 16 | 13
+ *
+ * This is equivalent to LPAE_SHIFT = PAGE_SHIFT - 3
*/
+#define LPAE_SHIFT_GS(gs) ((gs) - 3)
+#define LPAE_ENTRIES_GS(gs) (_AC(1, U) << LPAE_SHIFT_GS(gs))
+#define LPAE_ENTRIES_MASK_GS(gs) (LPAE_ENTRIES_GS(gs) - 1)
+
+#define LEVEL_ORDER_GS(gs, lvl) ((3 - (lvl)) * LPAE_SHIFT_GS(gs))
+#define LEVEL_SHIFT_GS(gs, lvl) (LEVEL_ORDER_GS(gs, lvl) + (gs))
+#define LEVEL_SIZE_GS(gs, lvl) (_AT(paddr_t, 1) << LEVEL_SHIFT_GS(gs, lvl))
-#define LPAE_SHIFT_4K (9)
-#define LPAE_SHIFT_16K (11)
-#define LPAE_SHIFT_64K (13)
-
-#define lpae_entries(gran) (_AC(1,U) << LPAE_SHIFT_##gran)
-#define lpae_entry_mask(gran) (lpae_entries(gran) - 1)
-
-#define third_shift(gran) (PAGE_SHIFT_##gran)
-#define third_size(gran) ((paddr_t)1 << third_shift(gran))
-
-#define second_shift(gran) (third_shift(gran) + LPAE_SHIFT_##gran)
-#define second_size(gran) ((paddr_t)1 << second_shift(gran))
-
-#define first_shift(gran) (second_shift(gran) + LPAE_SHIFT_##gran)
-#define first_size(gran) ((paddr_t)1 << first_shift(gran))
-
-/* Note that there is no zeroeth lookup level with a 64K granule size. */
-#define zeroeth_shift(gran) (first_shift(gran) + LPAE_SHIFT_##gran)
-#define zeroeth_size(gran) ((paddr_t)1 << zeroeth_shift(gran))
-
-#define TABLE_OFFSET(offs, gran) (offs & lpae_entry_mask(gran))
-#define TABLE_OFFSET_HELPERS(gran) \
-static inline paddr_t third_table_offset_##gran##K(paddr_t va) \
-{ \
- return TABLE_OFFSET((va >> third_shift(gran##K)), gran##K); \
-} \
- \
-static inline paddr_t second_table_offset_##gran##K(paddr_t va) \
-{ \
- return TABLE_OFFSET((va >> second_shift(gran##K)), gran##K); \
-} \
- \
-static inline paddr_t first_table_offset_##gran##K(paddr_t va) \
-{ \
- return TABLE_OFFSET((va >> first_shift(gran##K)), gran##K); \
-} \
- \
-static inline paddr_t zeroeth_table_offset_##gran##K(paddr_t va) \
-{ \
- /* Note that there is no zeroeth lookup level with 64K granule sizes. */\
- if ( gran == 64 ) \
- return 0; \
- else \
- return TABLE_OFFSET((va >> zeroeth_shift(gran##K)), gran##K); \
-} \
-
-TABLE_OFFSET_HELPERS(4);
-TABLE_OFFSET_HELPERS(16);
-TABLE_OFFSET_HELPERS(64);
-
-#undef TABLE_OFFSET
-#undef TABLE_OFFSET_HELPERS
+/* Offset in the table at level 'lvl' */
+#define LPAE_TABLE_INDEX_GS(gs, lvl, addr) \
+ (((addr) >> LEVEL_SHIFT_GS(gs, lvl)) & LPAE_ENTRIES_MASK_GS(gs))
/* Generate an array @var containing the offset for each level from @addr */
#define DECLARE_OFFSETS(var, addr) \
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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