[PATCH v2 01/11] KVM: arm64: initialize HCRX_EL2

Kristina Martsenko
2023-05-09T14:23:26Z

ARMv8.7/9.2 adds a new hypervisor configuration register HCRX_EL2.
Initialize the register to a safe value (all fields 0), to be robust
against firmware that has not initialized it. This is also needed to
ensure that the register is reinitialized after a kexec by a future
kernel.

In addition, move SMPME setup over to the new flags, as it would
otherwise get overridden. It is safe to set the bit even if SME is not
(uniformly) supported, as it will write to a RES0 bit (having no
effect), and SME will be disabled by the cpufeature framework.
(Similar to how e.g. the API bit is handled in HCR_HOST_NVHE_FLAGS.)

Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
---
arch/arm64/include/asm/el2_setup.h | 18 ++++++++++--------
arch/arm64/include/asm/kvm_arm.h | 3 +++
2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index 037724b19c5c..0201577863ca 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -22,6 +22,15 @@
isb
.endm

+.macro __init_el2_hcrx
+ mrs x0, id_aa64mmfr1_el1
+ ubfx x0, x0, #ID_AA64MMFR1_EL1_HCX_SHIFT, #4
+ cbz x0, .Lskip_hcrx_\@
+ mov_q x0, HCRX_HOST_FLAGS
+ msr_s SYS_HCRX_EL2, x0
+.Lskip_hcrx_\@:
+.endm
+
/*
* Allow Non-secure EL1 and EL0 to access physical timer and counter.
* This is not necessary for VHE, since the host kernel runs in EL2,
@@ -184,6 +193,7 @@
*/
.macro init_el2_state
__init_el2_sctlr
+ __init_el2_hcrx
__init_el2_timers
__init_el2_debug
__init_el2_lor
@@ -284,14 +294,6 @@
cbz x1, .Lskip_sme_\@

msr_s SYS_SMPRIMAP_EL2, xzr // Make all priorities equal
-
- mrs x1, id_aa64mmfr1_el1 // HCRX_EL2 present?
- ubfx x1, x1, #ID_AA64MMFR1_EL1_HCX_SHIFT, #4
- cbz x1, .Lskip_sme_\@
-
- mrs_s x1, SYS_HCRX_EL2
- orr x1, x1, #HCRX_EL2_SMPME_MASK // Enable priority mapping
- msr_s SYS_HCRX_EL2, x1
.Lskip_sme_\@:
.endm

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index baef29fcbeee..fb7fe28b8eb8 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -9,6 +9,7 @@

#include <asm/esr.h>
#include <asm/memory.h>
+#include <asm/sysreg.h>
#include <asm/types.h>

/* Hyp Configuration Register (HCR) bits */
@@ -92,6 +93,8 @@
#define HCR_HOST_NVHE_PROTECTED_FLAGS (HCR_HOST_NVHE_FLAGS | HCR_TSC)
#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)

+#define HCRX_HOST_FLAGS (HCRX_EL2_SMPME)
+
/* TCR_EL2 Registers bits */
#define TCR_EL2_RES1 ((1U << 31) | (1 << 23))
#define TCR_EL2_TBI (1 << 20)
--
2.25.1