Thread (18 messages) read the whole thread 18 messages, 3 authors, 2025-08-19

Re: [PATCH 2/4] arm64/sysreg: Replace TCR_EL1 field macros

From: Marc Zyngier <maz@kernel.org>
Date: 2025-08-18 15:47:02
Also in: kvmarm, lkml

On Mon, 18 Aug 2025 05:57:57 +0100,
Anshuman Khandual [off-list ref] wrote:
This just replaces all used TCR_EL1 field macros with tools sysreg variant
based fields and subsequently drops them from the header (pgtable-hwdef.h).
While here, also drop all the unused TCR_XXX macros from the header.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: kvmarm@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <redacted>
---
 arch/arm64/include/asm/assembler.h         |   6 +-
 arch/arm64/include/asm/cputype.h           |   2 +-
 arch/arm64/include/asm/kvm_arm.h           |  28 +++---
 arch/arm64/include/asm/kvm_nested.h        |   6 +-
 arch/arm64/include/asm/mmu_context.h       |   4 +-
 arch/arm64/include/asm/pgtable-hwdef.h     | 107 +++------------------
 arch/arm64/include/asm/pgtable-prot.h      |   2 +-
 arch/arm64/kernel/cpufeature.c             |   4 +-
 arch/arm64/kernel/pi/map_kernel.c          |   8 +-
 arch/arm64/kernel/vmcore_info.c            |   2 +-
 arch/arm64/kvm/arm.c                       |   6 +-
 arch/arm64/kvm/at.c                        |  48 ++++-----
 arch/arm64/kvm/hyp/include/hyp/switch.h    |   2 +-
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h |   2 +-
 arch/arm64/kvm/hyp/nvhe/switch.c           |   2 +-
 arch/arm64/kvm/hyp/nvhe/tlb.c              |   2 +-
 arch/arm64/kvm/hyp/vhe/tlb.c               |   2 +-
 arch/arm64/kvm/nested.c                    |   8 +-
 arch/arm64/kvm/pauth.c                     |  12 +--
 arch/arm64/mm/proc.S                       |  29 +++---
 tools/arch/arm64/include/asm/cputype.h     |   2 +-
 21 files changed, 101 insertions(+), 183 deletions(-)
[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 888f7c7abf54..b47d6d530e57 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2000,10 +2000,10 @@ static void __init cpu_prepare_hyp_mode(int cpu, u32 hyp_va_bits)
 
 	tcr = read_sysreg(tcr_el1);
 	if (cpus_have_final_cap(ARM64_KVM_HVHE)) {
-		tcr &= ~(TCR_HD | TCR_HA | TCR_A1 | TCR_T0SZ_MASK);
-		tcr |= TCR_EPD1_MASK;
+		tcr &= ~(TCR_EL1_HD | TCR_EL1_HA | TCR_EL1_A1 | TCR_EL1_T0SZ_MASK);
+		tcr |= TCR_EL1_EPD1_MASK;
Except that none of that code is about EL1. At all.
quoted hunk ↗ jump to hunk
 	} else {
-		unsigned long ips = FIELD_GET(TCR_IPS_MASK, tcr);
+		unsigned long ips = FIELD_GET(TCR_EL1_IPS_MASK, tcr);
 
 		tcr &= TCR_EL2_MASK;
 		tcr |= TCR_EL2_RES1 | FIELD_PREP(TCR_EL2_PS_MASK, ips);
diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
index 0e5610533949..5f0f10ef38f0 100644
--- a/arch/arm64/kvm/at.c
+++ b/arch/arm64/kvm/at.c
@@ -134,8 +134,8 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 	tbi = (wi->regime == TR_EL2 ?
 	       FIELD_GET(TCR_EL2_TBI, tcr) :
 	       (va55 ?
-		FIELD_GET(TCR_TBI1, tcr) :
-		FIELD_GET(TCR_TBI0, tcr)));
+		FIELD_GET(TCR_EL1_TBI1, tcr) :
+		FIELD_GET(TCR_EL1_TBI0, tcr)));
This is the reason number one why I dislike this patch.

Here, we deal with both the EL1&0 *and* the EL2&0 translation
regimes. And I left the original definition *on purpose* so that
nobody would read this code as being EL1-only. Now, you will glance
over it with warm fuzzy feeling that you know what this is about --
purely EL1. And that's what bugs are made of.

Of course, nothing changed functionally. But is it better? No.

	M.

-- 
Jazz isn't dead. It just smells funny.
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