| From a6daca56b77d7f1b26483f10eb33ebdd6e157d3e Mon Sep 17 00:00:00 2001 |
| From: Peter Hoyes <Peter.Hoyes@arm.com> |
| Date: Fri, 10 Dec 2021 16:37:26 +0000 |
| Subject: [PATCH 5/9] armv8: Make disabling HVC configurable when switching to |
| EL1 |
| |
| On the BASER_FVP there is no EL3, so HVC is used to provide PSCI |
| services. Therefore we cannot disable hypercalls. |
| |
| Create CONFIG_ARMV8_DISABLE_HVC (dependent on CONFIG_ARMV8_TO_EL1) to |
| control whether to disable HVC exceptions in HCR_EL2->HCD |
| |
| Issue-Id: SCM-3728 |
| Upstream-Status: Inappropriate [other] |
| Implementation pending further discussion |
| Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com> |
| Change-Id: I463d82f1db8a3cafcab40a9c0c208753569cc300 |
| --- |
| arch/arm/cpu/armv8/Kconfig | 9 +++++++++ |
| arch/arm/include/asm/macro.h | 10 ++++++++-- |
| configs/vexpress_aemv8r_defconfig | 1 + |
| 3 files changed, 18 insertions(+), 2 deletions(-) |
| |
| diff --git a/arch/arm/cpu/armv8/Kconfig b/arch/arm/cpu/armv8/Kconfig |
| index dec4be0e30..95c03487a2 100644 |
| --- a/arch/arm/cpu/armv8/Kconfig |
| +++ b/arch/arm/cpu/armv8/Kconfig |
| @@ -208,4 +208,13 @@ config ARMV8_CE_SHA256 |
| |
| endif |
| |
| +config ARMV8_DISABLE_HVC |
| + bool "Disable HVC calls before switching to EL1" |
| + depends on ARMV8_SWITCH_TO_EL1 |
| + default y |
| + help |
| + If switching to EL1 before loading the operating system, disable taking |
| + hypercalls back to EL2. May be disabled if, for example, PSCI services are |
| + running at EL2. |
| + |
| endif |
| diff --git a/arch/arm/include/asm/macro.h b/arch/arm/include/asm/macro.h |
| index 1a1edc9870..7167739210 100644 |
| --- a/arch/arm/include/asm/macro.h |
| +++ b/arch/arm/include/asm/macro.h |
| @@ -296,9 +296,12 @@ lr .req x30 |
| ldr \tmp2, =(ID_AA64ISAR1_EL1_GPI | ID_AA64ISAR1_EL1_GPA | \ |
| ID_AA64ISAR1_EL1_API | ID_AA64ISAR1_EL1_APA) |
| tst \tmp, \tmp2 |
| - mov \tmp2, #(HCR_EL2_RW_AARCH64 | HCR_EL2_HCD_DIS) |
| + mov \tmp2, #(HCR_EL2_RW_AARCH64) |
| orr \tmp, \tmp2, #(HCR_EL2_APK | HCR_EL2_API) |
| csel \tmp, \tmp2, \tmp, eq |
| +#ifdef CONFIG_ARMV8_DISABLE_HVC |
| + orr \tmp, \tmp, #(HCR_EL2_HCD_DIS) |
| +#endif |
| msr hcr_el2, \tmp |
| |
| /* Return to the EL1_SP1 mode from EL2 */ |
| @@ -311,7 +314,10 @@ lr .req x30 |
| |
| 1: |
| /* Initialize HCR_EL2 */ |
| - ldr \tmp, =(HCR_EL2_RW_AARCH32 | HCR_EL2_HCD_DIS) |
| + ldr \tmp, =(HCR_EL2_RW_AARCH32) |
| +#ifdef CONFIG_ARMV8_DISABLE_HVC |
| + orr \tmp, \tmp, #(HCR_EL2_HCD_DIS) |
| +#endif |
| msr hcr_el2, \tmp |
| |
| /* Return to AArch32 Supervisor mode from EL2 */ |
| diff --git a/configs/vexpress_aemv8r_defconfig b/configs/vexpress_aemv8r_defconfig |
| index 6044f82b00..6226f6b2c1 100644 |
| --- a/configs/vexpress_aemv8r_defconfig |
| +++ b/configs/vexpress_aemv8r_defconfig |
| @@ -18,3 +18,4 @@ CONFIG_SYS_PBSIZE=541 |
| CONFIG_VIRTIO_MMIO=y |
| CONFIG_ARMV8_EXCEPTION_VECTORS=n |
| CONFIG_ARMV8_SWITCH_TO_EL1=y |
| +CONFIG_ARMV8_DISABLE_HVC=n |
| -- |
| 2.25.1 |
| |