[PATCH v2 07/14] arm64: Make the PHYS_MASK_SHIFT dynamic

Steven Price
2024-04-12T08:42:38Z

Make the PHYS_MASK_SHIFT dynamic for Realms. This is only is required
for masking the PFN from a pte entry. Elsewhere, we could still use the
PA bits configured by the kernel. So, this patch:

-> renames PHYS_MASK_SHIFT -> MAX_PHYS_SHIFT as supported by the kernel
-> Makes PHYS_MASK_SHIFT -> Dynamic value of the (I)PA bit width
-> For a realm: reduces phys_mask_shift if the RMM reports a smaller
configured size for the guest.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/include/asm/kvm_arm.h | 2 +-
arch/arm64/include/asm/pgtable-hwdef.h | 4 ++--
arch/arm64/include/asm/pgtable.h | 5 +++++
arch/arm64/kernel/rsi.c | 5 +++++
4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index e01bb5ca13b7..9944aca348bd 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -398,7 +398,7 @@
* bits in PAR are res0.
*/
#define PAR_TO_HPFAR(par) \
- (((par) & GENMASK_ULL(52 - 1, 12)) >> 8)
+ (((par) & GENMASK_ULL(MAX_PHYS_MASK_SHIFT - 1, 12)) >> 8)

#define ECN(x) { ESR_ELx_EC_##x, #x }

diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index ef207a0d4f0d..90dc292bed5f 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -206,8 +206,8 @@
/*
* Highest possible physical address supported.
*/
-#define PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
-#define PHYS_MASK ((UL(1) << PHYS_MASK_SHIFT) - 1)
+#define MAX_PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
+#define MAX_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 afdd56d26ad7..f5376bd567a1 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)
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE

diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index b93252ed6fc5..159bc428c77b 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -12,6 +12,8 @@ struct realm_config __attribute((aligned(PAGE_SIZE))) config;
unsigned long prot_ns_shared;
EXPORT_SYMBOL(prot_ns_shared);

+unsigned int phys_mask_shift = CONFIG_ARM64_PA_BITS;
+
DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
EXPORT_SYMBOL(rsi_present);

@@ -62,5 +64,8 @@ void __init arm64_rsi_init(void)
return;
prot_ns_shared = BIT(config.ipa_bits - 1);

+ if (config.ipa_bits - 1 < phys_mask_shift)
+ phys_mask_shift = config.ipa_bits - 1;
+
static_branch_enable(&rsi_present);
}
--
2.34.1