From 9cce9c6c2c3b7d46698d9bb693389d37740fec28 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 14 Feb 2024 13:29:11 +0100 Subject: arm64: mm: Handle LVA support as a CPU feature Currently, we detect CPU support for 52-bit virtual addressing (LVA) extremely early, before creating the kernel page tables or enabling the MMU. We cannot override the feature this early, and so large virtual addressing is always enabled on CPUs that implement support for it if the software support for it was enabled at build time. It also means we rely on non-trivial code in asm to deal with this feature. Given that both the ID map and the TTBR1 mapping of the kernel image are guaranteed to be 48-bit addressable, it is not actually necessary to enable support this early, and instead, we can model it as a CPU feature. That way, we can rely on code patching to get the correct TCR.T1SZ values programmed on secondary boot and resume from suspend. On the primary boot path, we simply enable the MMU with 48-bit virtual addressing initially, and update TCR.T1SZ if LVA is supported from C code, right before creating the kernel mapping. Given that TTBR1 still points to reserved_pg_dir at this point, updating TCR.T1SZ should be safe without the need for explicit TLB maintenance. Since this gets rid of all accesses to the vabits_actual variable from asm code that occurred before TCR.T1SZ had been programmed, we no longer have a need for this variable, and we can replace it with a C expression that produces the correct value directly, based on the value of TCR.T1SZ. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-70-ardb+git@google.com Signed-off-by: Catalin Marinas --- arch/arm64/tools/cpucaps | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm64/tools/cpucaps') diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index b912b1409fc0..b370d808b3ec 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -50,6 +50,7 @@ HAS_STAGE2_FWB HAS_TCR2 HAS_TIDCP1 HAS_TLB_RANGE +HAS_VA52 HAS_VIRT_HOST_EXTN HAS_WFXT HW_DBM -- cgit v1.2.3