[PATCH v2] irqchip/gic-v5: Preserve ICC_CR0_EL1 state

[PATCH v2] irqchip/gic-v5: Preserve ICC_CR0_EL1 state

[Sascha Bischoff]

In addition to EN, ICC_CR0_EL1 contains other fields, such as LINK and
LINK_IDLE. The driver only needs to modify EN, and must preserve the
values of all other fields when enabling or disabling the CPU
interface.

Define the missing LINK and LINK_IDLE fields, and use read-modify-write
accesses to update EN without affecting the rest of ICC_CR0_EL1.

Fixes: 7ec80fb3f025 ("irqchip/gic-v5: Add GICv5 PPI support")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/r/20260807121703.D4B7A1F00A3A@smtp.kernel.org
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
 arch/arm64/tools/sysreg      | 4 +++-
 drivers/irqchip/irq-gic-v5.c | 6 ++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
index 94bf065c8ac7..e2d37ee221b8 100644
--- a/arch/arm64/tools/sysreg
+++ b/arch/arm64/tools/sysreg
@@ -3761,7 +3761,9 @@ Sysreg	ICC_CR0_EL1	3	1	12	0	1
 Res0	63:39
 Field	38	PID
 Field	37:32	IPPT
-Res0	31:1
+Res0	31:3
+Field	2	LINK_IDLE
+Field	1	LINK
 Field	0	EN
 EndSysreg
 
diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
index ac2d423b1723..5f2551cf077d 100644
--- a/drivers/irqchip/irq-gic-v5.c
+++ b/drivers/irqchip/irq-gic-v5.c
@@ -974,7 +974,8 @@ static void gicv5_cpu_disable_interrupts(void)
 {
 	u64 cr0;
 
-	cr0 = FIELD_PREP(ICC_CR0_EL1_EN, 0);
+	cr0 = read_sysreg_s(SYS_ICC_CR0_EL1);
+	cr0 &= ~ICC_CR0_EL1_EN_MASK;
 	write_sysreg_s(cr0, SYS_ICC_CR0_EL1);
 	isb();
 }
@@ -991,7 +992,8 @@ static void gicv5_cpu_enable_interrupts(void)
 	pcr = FIELD_PREP(ICC_PCR_EL1_PRIORITY, GICV5_IRQ_PRI_MI);
 	write_sysreg_s(pcr, SYS_ICC_PCR_EL1);
 
-	cr0 = FIELD_PREP(ICC_CR0_EL1_EN, 1);
+	cr0 = read_sysreg_s(SYS_ICC_CR0_EL1);
+	cr0 |= ICC_CR0_EL1_EN_MASK;
 	write_sysreg_s(cr0, SYS_ICC_CR0_EL1);
 }
 
-- 
2.34.1

Re: [PATCH v2] irqchip/gic-v5: Preserve ICC_CR0_EL1 state

[Marc Zyngier]

On Mon, 07 Sep 2026 17:49:50 +0100,
Sascha Bischoff <Sascha.Bischoff@arm.com> wrote:
> 
> In addition to EN, ICC_CR0_EL1 contains other fields, such as LINK and
> LINK_IDLE. The driver only needs to modify EN, and must preserve the
> values of all other fields when enabling or disabling the CPU
> interface.
> 
> Define the missing LINK and LINK_IDLE fields, and use read-modify-write
> accesses to update EN without affecting the rest of ICC_CR0_EL1.
> 
> Fixes: 7ec80fb3f025 ("irqchip/gic-v5: Add GICv5 PPI support")
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://lore.kernel.org/r/20260807121703.D4B7A1F00A3A@smtp.kernel.org
> Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.