On 09/07/2024 12:43, Will Deacon wrote:
On Mon, Jul 01, 2024 at 10:54:56AM +0100, Steven Price wrote:
Make the PHYS_MASK_SHIFT dynamic for Realms. This is only is required
for masking the PFN from a pte entry. For a realm phys_mask_shift is
reduced if the RMM reports a smaller configured size for the guest.
The realm configuration splits the address space into two with the top
half being memory shared with the host, and the bottom half being
protected memory. We treat the bit which controls this split as an
attribute bit and hence exclude it (and any higher bits) from the mask.
Co-developed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
v3: Drop the MAX_PHYS_MASK{,_SHIFT} definitions as they are no longer
needed.
---
arch/arm64/include/asm/pgtable-hwdef.h | 6 ------
arch/arm64/include/asm/pgtable.h | 5 +++++
arch/arm64/kernel/rsi.c | 5 +++++
3 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 9943ff0af4c9..2e3af0693bd8 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -203,12 +203,6 @@
*/
#define PTE_S2_MEMATTR(t) (_AT(pteval_t, (t)) << 2)
-/*
- * Highest possible physical address supported.
- */
-#define PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
-#define PHYS_MASK ((UL(1) << PHYS_MASK_SHIFT) - 1)
-
#define TTBR_CNP_BIT (UL(1) << 0)
/*
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index f8efbc128446..11d614d83317 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -39,6 +39,11 @@
#include <linux/sched.h>
#include <linux/page_table_check.h>
+extern unsigned int phys_mask_shift;
+
+#define PHYS_MASK_SHIFT (phys_mask_shift)
+#define PHYS_MASK ((1UL << PHYS_MASK_SHIFT) - 1)
I tried to figure out where this is actually used so I could understand
your comment in the commit message:
> This is only is required for masking the PFN from a pte entry
The closest thing I could find is in arch/arm64/mm/mmap.c, where the
mask is used as part of valid_mmap_phys_addr_range() which exists purely
to filter accesses to /dev/mem. That's pretty niche, so why not just
inline the RSI-specific stuff in there behind a static key instead of
changing these definitions?
Or did I miss a subtle user somewhere else?
We need to prevent ioremap() of addresses beyond that limit too.
Suzuki
Will
