[PATCH 6.18 211/212] arm64: realm: Fix PTE_NS_SHARED for 52bit PA support

Greg Kroah-Hartman
2026-03-23T14:11:16Z

From: Suzuki K Poulose <suzuki.poulose@arm.com>

[ Upstream commit 8c6e9b60f5c7985a9fe41320556a92d7a33451df ]

With LPA/LPA2, the top bits of the PFN (Bits[51:48]) end up in the lower bits
of the PTE. So, simply creating a mask of the "top IPA bit" doesn't work well
for these configurations to set the "top" bit at the output of Stage1
translation.

Fix this by using the __phys_to_pte_val() to do the right thing for all
configurations.

Tested using, kvmtool, placing the memory at a higher address (-m <size>@<Addr>).

e.g:
# lkvm run --realm -c 4 -m 512M@@128T -k Image --console serial

sh-5.0# dmesg | grep "LPA2\|RSI"
[ 0.000000] RME: Using RSI version 1.0
[ 0.000000] CPU features: detected: 52-bit Virtual Addressing (LPA2)
[ 0.777354] CPU features: detected: 52-bit Virtual Addressing for KVM (LPA2)

Fixes: 399306954996 ("arm64: realm: Query IPA size from the RMM")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kernel/rsi.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index c64a06f58c0bc..9e846ce4ef9ca 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -12,6 +12,7 @@

#include <asm/io.h>
#include <asm/mem_encrypt.h>
+#include <asm/pgtable.h>
#include <asm/rsi.h>

static struct realm_config config;
@@ -146,7 +147,7 @@ void __init arm64_rsi_init(void)
return;
if (WARN_ON(rsi_get_realm_config(&config)))
return;
- prot_ns_shared = BIT(config.ipa_bits - 1);
+ prot_ns_shared = __phys_to_pte_val(BIT(config.ipa_bits - 1));

if (arm64_ioremap_prot_hook_register(realm_ioremap_hook))
return;
--
2.51.0