From: Julien Grall <julien@xen.org>
To: xen-devel@lists.xenproject.org
Cc: Luca.Fancellu@arm.com, michal.orzel@amd.com,
Julien Grall <jgrall@amazon.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Luca Fancellu <luca.fancellu@arm.com>
Subject: [PATCH v7 5/5] xen/arm64: smpboot: Directly switch to the runtime page-tables
Date: Sun, 16 Apr 2023 15:32:11 +0100 [thread overview]
Message-ID: <20230416143211.72227-6-julien@xen.org> (raw)
In-Reply-To: <20230416143211.72227-1-julien@xen.org>
From: Julien Grall <jgrall@amazon.com>
Switching TTBR while the MMU is on is not safe. Now that the identity
mapping will not clash with the rest of the memory layout, we can avoid
creating temporary page-tables every time a CPU is brought up.
The arm32 code will use a different approach. So this issue is for now
only resolved on arm64.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
----
Changes in v7:
- Remove the tested-by tag because of the layout reshuffle in
the previous patches.
Changes in v6:
- Add Bertrand's reviewed-by
Changes in v5:
- Add Luca's reviewed-by and tested-by tags.
Changes in v4:
- Somehow I forgot to send it in v3. So re-include it.
Changes in v2:
- Remove arm32 code
---
xen/arch/arm/arm32/smpboot.c | 4 ++++
xen/arch/arm/arm64/head.S | 29 +++++++++--------------------
xen/arch/arm/arm64/smpboot.c | 15 ++++++++++++++-
xen/arch/arm/include/asm/smp.h | 1 +
xen/arch/arm/smpboot.c | 1 +
5 files changed, 29 insertions(+), 21 deletions(-)
diff --git a/xen/arch/arm/arm32/smpboot.c b/xen/arch/arm/arm32/smpboot.c
index e7368665d50d..518e9f9c7e70 100644
--- a/xen/arch/arm/arm32/smpboot.c
+++ b/xen/arch/arm/arm32/smpboot.c
@@ -21,6 +21,10 @@ int arch_cpu_up(int cpu)
return platform_cpu_up(cpu);
}
+void arch_cpu_up_finish(void)
+{
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 5efd442b24af..a61b4d3c2738 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -308,6 +308,7 @@ real_start_efi:
bl check_cpu_mode
bl cpu_init
bl create_page_tables
+ load_paddr x0, boot_pgtable
bl enable_mmu
/* We are still in the 1:1 mapping. Jump to the runtime Virtual Address. */
@@ -365,29 +366,14 @@ GLOBAL(init_secondary)
#endif
bl check_cpu_mode
bl cpu_init
- bl create_page_tables
+ load_paddr x0, init_ttbr
+ ldr x0, [x0]
bl enable_mmu
/* We are still in the 1:1 mapping. Jump to the runtime Virtual Address. */
ldr x0, =secondary_switched
br x0
secondary_switched:
- /*
- * Non-boot CPUs need to move on to the proper pagetables, which were
- * setup in init_secondary_pagetables.
- *
- * XXX: This is not compliant with the Arm Arm.
- */
- ldr x4, =init_ttbr /* VA of TTBR0_EL2 stashed by CPU 0 */
- ldr x4, [x4] /* Actual value */
- dsb sy
- msr TTBR0_EL2, x4
- dsb sy
- isb
- tlbi alle2
- dsb sy /* Ensure completion of TLB flush */
- isb
-
#ifdef CONFIG_EARLY_PRINTK
/* Use a virtual address to access the UART. */
ldr x23, =EARLY_UART_VIRTUAL_ADDRESS
@@ -672,9 +658,13 @@ ENDPROC(create_page_tables)
* mapping. In other word, the caller is responsible to switch to the runtime
* mapping.
*
- * Clobbers x0 - x3
+ * Inputs:
+ * x0 : Physical address of the page tables.
+ *
+ * Clobbers x0 - x4
*/
enable_mmu:
+ mov x4, x0
PRINT("- Turning on paging -\r\n")
/*
@@ -685,8 +675,7 @@ enable_mmu:
dsb nsh
/* Write Xen's PT's paddr into TTBR0_EL2 */
- load_paddr x0, boot_pgtable
- msr TTBR0_EL2, x0
+ msr TTBR0_EL2, x4
isb
mrs x0, SCTLR_EL2
diff --git a/xen/arch/arm/arm64/smpboot.c b/xen/arch/arm/arm64/smpboot.c
index 694fbf67e62a..9637f424699e 100644
--- a/xen/arch/arm/arm64/smpboot.c
+++ b/xen/arch/arm/arm64/smpboot.c
@@ -106,10 +106,23 @@ int __init arch_cpu_init(int cpu, struct dt_device_node *dn)
int arch_cpu_up(int cpu)
{
+ int rc;
+
if ( !smp_enable_ops[cpu].prepare_cpu )
return -ENODEV;
- return smp_enable_ops[cpu].prepare_cpu(cpu);
+ update_identity_mapping(true);
+
+ rc = smp_enable_ops[cpu].prepare_cpu(cpu);
+ if ( rc )
+ update_identity_mapping(false);
+
+ return rc;
+}
+
+void arch_cpu_up_finish(void)
+{
+ update_identity_mapping(false);
}
/*
diff --git a/xen/arch/arm/include/asm/smp.h b/xen/arch/arm/include/asm/smp.h
index 8133d5c29572..a37ca55bff2c 100644
--- a/xen/arch/arm/include/asm/smp.h
+++ b/xen/arch/arm/include/asm/smp.h
@@ -25,6 +25,7 @@ extern void noreturn stop_cpu(void);
extern int arch_smp_init(void);
extern int arch_cpu_init(int cpu, struct dt_device_node *dn);
extern int arch_cpu_up(int cpu);
+extern void arch_cpu_up_finish(void);
int cpu_up_send_sgi(int cpu);
diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index 412ae2286906..4a89b3a8345b 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -500,6 +500,7 @@ int __cpu_up(unsigned int cpu)
init_data.cpuid = ~0;
smp_up_cpu = MPIDR_INVALID;
clean_dcache(smp_up_cpu);
+ arch_cpu_up_finish();
if ( !cpu_online(cpu) )
{
--
2.39.2
next prev parent reply other threads:[~2023-04-16 14:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-16 14:32 [PATCH v7 0/5] xen/arm: Don't switch TTBR while the MMU is on Julien Grall
2023-04-16 14:32 ` [PATCH v7 1/5] xen/arm32: head: Widen the use of the temporary mapping Julien Grall
2023-04-18 13:51 ` Bertrand Marquis
2023-06-10 18:49 ` Julien Grall
2023-04-16 14:32 ` [PATCH v7 2/5] xen/arm64: Rework the memory layout Julien Grall
2023-04-17 4:58 ` Henry Wang
2023-04-17 7:21 ` Luca Fancellu
2023-04-17 7:28 ` Michal Orzel
2023-04-19 18:38 ` Julien Grall
2023-04-18 13:53 ` Bertrand Marquis
2023-04-18 13:58 ` Bertrand Marquis
2023-04-16 14:32 ` [PATCH v7 3/5] xen/arm64: mm: Introduce helpers to prepare/enable/disable the identity mapping Julien Grall
2023-04-17 4:59 ` Henry Wang
2023-04-17 7:46 ` Luca Fancellu
2023-04-17 7:55 ` Michal Orzel
2023-04-18 13:57 ` Bertrand Marquis
2023-04-16 14:32 ` [PATCH v7 4/5] xen/arm64: mm: Rework switch_ttbr() Julien Grall
2023-04-17 4:59 ` Henry Wang
2023-04-16 14:32 ` Julien Grall [this message]
2023-04-17 4:59 ` [PATCH v7 5/5] xen/arm64: smpboot: Directly switch to the runtime page-tables Henry Wang
2023-04-19 18:42 ` [PATCH v7 0/5] xen/arm: Don't switch TTBR while the MMU is on Julien Grall
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