linux-kernel - [RFC kvm-unit-tests 06/27] arm: Move io

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Date:   Fri, 27 Jan 2023 11:40:47 +0000
From:   Joey Gouly <joey.gouly@....com>
To:     Andrew Jones <andrew.jones@...ux.dev>, <kvmarm@...ts.linux.dev>,
        <kvm@...r.kernel.org>
CC:     <joey.gouly@....com>, Alexandru Elisei <alexandru.elisei@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Fuad Tabba <tabba@...gle.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Joey Gouly <Joey.Gouly@....com>, Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Quentin Perret <qperret@...gle.com>,
        Steven Price <steven.price@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        "Thomas Huth" <thuth@...hat.com>, Will Deacon <will@...nel.org>,
        Zenghui Yu <yuzenghui@...wei.com>,
        <linux-coco@...ts.linux.dev>, <kvmarm@...ts.cs.columbia.edu>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [RFC kvm-unit-tests 06/27] arm: Move io_init after vm initialization

From: Jean-Philippe Brucker <jean-philippe@...aro.org>

To create shared pages, the NS_SHARED bit must be written into the
idmap. Before VM initializations, idmap hasn't necessarily been created.
To write shared pages, access must be done on a IPA with the NS_SHARED
bit. When the stage-1 MMU is enabled, that bit is set in the PTE. But
when the stage-1 MMU is disabled, then the realm must write to the IPA
with NS_SHARED directly.

To avoid changing the whole virtio infrastructure to support pre-MMU in
a realm, move the IO initialization after MMU enablement.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
Signed-off-by: Joey Gouly <joey.gouly@....com>
---
 lib/arm/setup.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/arm/setup.c b/lib/arm/setup.c
index 81052a3d..65d98e97 100644
--- a/lib/arm/setup.c
+++ b/lib/arm/setup.c
@@ -274,9 +274,6 @@ void setup(const void *fdt, phys_addr_t freemem_start)
 	/* cpu_init must be called before thread_info_init */
 	thread_info_init(current_thread_info(), 0);
 
-	/* mem_init must be called before io_init */
-	io_init();
-
 	timer_save_state();
 
 	ret = dt_get_bootargs(&bootargs);
@@ -292,4 +289,7 @@ void setup(const void *fdt, phys_addr_t freemem_start)
 
 	if (!(auxinfo.flags & AUXINFO_MMU_OFF))
 		setup_vm();
+
+	/* mem_init and setup_vm must be called before io_init */
+	io_init();
 }
-- 
2.17.1