[PATCH v5 14/37] arm64/gcs: Allow GCS usage at EL0 and EL1

Mark Brown
2023-08-22T14:05:07Z

There is a control HCRX_EL2.GCSEn which must be set to allow GCS
features to take effect at lower ELs and also fine grained traps for GCS
usage at EL0 and EL1. Configure all these to allow GCS usage by EL0 and
EL1.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/el2_setup.h | 17 +++++++++++++++++
arch/arm64/include/asm/kvm_arm.h | 4 ++--
2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index b7afaa026842..17672563e333 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -27,6 +27,14 @@
ubfx x0, x0, #ID_AA64MMFR1_EL1_HCX_SHIFT, #4
cbz x0, .Lskip_hcrx_\@
mov_q x0, HCRX_HOST_FLAGS
+
+ /* Enable GCS if supported */
+ mrs_s x1, SYS_ID_AA64PFR1_EL1
+ ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
+ cbz x1, .Lset_hcrx_\@
+ orr x0, x0, #HCRX_EL2_GCSEn
+
+.Lset_hcrx_\@:
msr_s SYS_HCRX_EL2, x0
.Lskip_hcrx_\@:
.endm
@@ -190,6 +198,15 @@
orr x0, x0, #HFGxTR_EL2_nPIR_EL1
orr x0, x0, #HFGxTR_EL2_nPIRE0_EL1

+ /* GCS depends on PIE so we don't check it if PIE is absent */
+ mrs_s x1, SYS_ID_AA64PFR1_EL1
+ ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
+ cbz x1, .Lset_fgt_\@
+
+ /* Disable traps of access to GCS registers at EL0 and EL1 */
+ orr x0, x0, #HFGxTR_EL2_nGCS_EL1_MASK
+ orr x0, x0, #HFGxTR_EL2_nGCS_EL0_MASK
+
.Lset_fgt_\@:
msr_s SYS_HFGRTR_EL2, x0
msr_s SYS_HFGWTR_EL2, x0
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 58e5eb27da68..9c84e200217b 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -94,8 +94,8 @@
#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_GUEST_FLAGS (HCRX_EL2_SMPME | HCRX_EL2_TCR2En)
-#define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn | HCRX_EL2_TCR2En)
+#define HCRX_GUEST_FLAGS (HCRX_EL2_SMPME | HCRX_EL2_TCR2En | HCRX_EL2_GCSEn)
+#define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn | HCRX_EL2_TCR2En | HCRX_EL2_GCSEn)

/* TCR_EL2 Registers bits */
#define TCR_EL2_RES1 ((1U << 31) | (1 << 23))

--
2.30.2