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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] kconfig: turn PDX compression into a choice
commit b541c627b227ecdca53602a31628d9b94218a0a6
Author: Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Mon May 26 16:42:49 2025 +0200
Commit: Roger Pau Monne <roger.pau@xxxxxxxxxx>
CommitDate: Mon Aug 11 18:45:05 2025 +0200
kconfig: turn PDX compression into a choice
Rename the current CONFIG_PDX_COMPRESSION to CONFIG_PDX_MASK_COMPRESSION,
and make it part of the PDX compression choice block, in preparation for
adding further PDX compression algorithms.
The PDX compression defaults should still be the same for all
architectures, however the choice block cannot be protected under EXPERT
and still have a default choice being unconditionally selected. As a
result, the new "PDX (Page inDeX) compression" item will be unconditionally
visible in Kconfig, even on architectures like x86 that previously had no
way to enable PDX compression.
As part of this preparation work to introduce new PDX compressions, adjust
some of the comments on pdx.h to note they apply to a specific PDX
compression. Also shuffle function prototypes and dummy implementations
around to make it easier to introduce a new PDX compression. Note all
PDX compression implementations are expected to provide a
pdx_is_region_compressible() that takes the same set of arguments.
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
xen/arch/arm/setup.c | 2 +-
xen/common/Kconfig | 18 +++++++++++++++---
xen/common/pdx.c | 4 ++--
xen/include/xen/pdx.h | 32 +++++++++++++++++++-------------
4 files changed, 37 insertions(+), 19 deletions(-)
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index bb35afe56c..a77b31071e 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -258,7 +258,7 @@ void __init init_pdx(void)
paddr_t bank_start, bank_size, bank_end, ram_end = 0;
int bank;
-#ifdef CONFIG_PDX_COMPRESSION
+#ifndef CONFIG_PDX_NONE
/*
* Arm does not have any restrictions on the bits to compress. Pass 0 to
* let the common code further restrict the mask.
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index 16936418a6..8dad0c923a 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -57,9 +57,10 @@ config EVTCHN_FIFO
If unsure, say Y.
-config PDX_COMPRESSION
- bool "PDX (Page inDeX) compression" if EXPERT && !X86 && !RISCV
- default ARM || PPC
+choice
+ prompt "PDX (Page inDeX) compression"
+ default PDX_MASK_COMPRESSION if !X86 && !RISCV
+ default PDX_NONE
help
PDX compression is a technique designed to reduce the memory
overhead of physical memory management on platforms with sparse RAM
@@ -72,6 +73,17 @@ config PDX_COMPRESSION
If your platform does not have sparse RAM banks, do not enable PDX
compression.
+config PDX_MASK_COMPRESSION
+ bool "Mask compression"
+ help
+ Compression relying on all RAM addresses sharing a zeroed bit region.
+
+config PDX_NONE
+ bool "None"
+ help
+ No compression
+endchoice
+
config ALTERNATIVE_CALL
bool
diff --git a/xen/common/pdx.c b/xen/common/pdx.c
index b8384e6189..00aa7e4300 100644
--- a/xen/common/pdx.c
+++ b/xen/common/pdx.c
@@ -34,7 +34,7 @@ bool __mfn_valid(unsigned long mfn)
{
bool invalid = mfn >= max_page;
-#ifdef CONFIG_PDX_COMPRESSION
+#ifdef CONFIG_PDX_MASK_COMPRESSION
invalid |= mfn & pfn_hole_mask;
#endif
@@ -55,7 +55,7 @@ void set_pdx_range(unsigned long smfn, unsigned long emfn)
__set_bit(idx, pdx_group_valid);
}
-#ifdef CONFIG_PDX_COMPRESSION
+#ifdef CONFIG_PDX_MASK_COMPRESSION
/*
* Diagram to make sense of the following variables. The masks and shifts
diff --git a/xen/include/xen/pdx.h b/xen/include/xen/pdx.h
index c1423d64a9..8e373cac8b 100644
--- a/xen/include/xen/pdx.h
+++ b/xen/include/xen/pdx.h
@@ -25,7 +25,7 @@
* this by keeping a bitmap of the ranges in the frame table containing
* invalid entries and not allocating backing memory for them.
*
- * ## PDX compression
+ * ## PDX mask compression
*
* This is a technique to avoid wasting memory on machines known to have
* split their machine address space in several big discontinuous and highly
@@ -101,22 +101,13 @@ bool __mfn_valid(unsigned long mfn);
#define paddr_to_pdx(pa) pfn_to_pdx(paddr_to_pfn(pa))
#define pdx_to_paddr(px) pfn_to_paddr(pdx_to_pfn(px))
-#ifdef CONFIG_PDX_COMPRESSION
+#ifdef CONFIG_PDX_MASK_COMPRESSION
extern unsigned long pfn_pdx_bottom_mask, ma_va_bottom_mask;
extern unsigned int pfn_pdx_hole_shift;
extern unsigned long pfn_hole_mask;
extern unsigned long pfn_top_mask, ma_top_mask;
-/**
- * Validate a region's compatibility with the current compression runtime
- *
- * @param base Base address of the region
- * @param npages Number of PAGE_SIZE-sized pages in the region
- * @return True iff the region can be used with the current compression
- */
-bool pdx_is_region_compressible(paddr_t base, unsigned long npages);
-
/**
* Calculates a mask covering "moving" bits of all addresses of a region
*
@@ -209,7 +200,9 @@ static inline paddr_t directmapoff_to_maddr(unsigned long
offset)
*/
void pfn_pdx_hole_setup(unsigned long mask);
-#else /* !CONFIG_PDX_COMPRESSION */
+#endif /* CONFIG_PDX_MASK_COMPRESSION */
+
+#ifdef CONFIG_PDX_NONE
/* Without PDX compression we can skip some computations */
@@ -241,7 +234,20 @@ static inline void pfn_pdx_hole_setup(unsigned long mask)
{
}
-#endif /* CONFIG_PDX_COMPRESSION */
+#else /* !CONFIG_PDX_NONE */
+
+/* Shared functions implemented by all PDX compressions. */
+
+/**
+ * Validate a region's compatibility with the current compression runtime
+ *
+ * @param base Base address of the region
+ * @param npages Number of PAGE_SIZE-sized pages in the region
+ * @return True iff the region can be used with the current compression
+ */
+bool pdx_is_region_compressible(paddr_t base, unsigned long npages);
+
+#endif /* !CONFIG_PDX_NONE */
#endif /* __XEN_PDX_H__ */
/*
--
generated by git-patchbot for /home/xen/git/xen.git#master
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