On Mon, Mar 31, 2025 at 05:43:15PM +0800, Yicong Yang wrote:
From: Yicong Yang yangyicong@hisilicon.com
Instructions introduced by FEAT_{LS64, LS64_V} is controlled by HCRX_EL2.{EnALS, EnASR}. Configure all of these to allow usage at EL0/1.
This doesn't mean these instructions are always available in EL0/1 if provided. The hypervisor still have the control at runtime.
Signed-off-by: Yicong Yang yangyicong@hisilicon.com
arch/arm64/include/asm/el2_setup.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h index ebceaae3c749..0259941602c4 100644 --- a/arch/arm64/include/asm/el2_setup.h +++ b/arch/arm64/include/asm/el2_setup.h @@ -57,9 +57,19 @@ /* Enable GCS if supported */ mrs_s x1, SYS_ID_AA64PFR1_EL1 ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
- cbz x1, .Lset_hcrx_@
- cbz x1, .Lskip_gcs_hcrx_@ orr x0, x0, #HCRX_EL2_GCSEn
+.Lskip_gcs_hcrx_@:
- /* Enable LS64, LS64_V if supported */
- mrs_s x1, SYS_ID_AA64ISAR1_EL1
- ubfx x1, x1, #ID_AA64ISAR1_EL1_LS64_SHIFT, #4
- cbz x1, .Lset_hcrx_@
- orr x0, x0, #HCRX_EL2_EnALS
- cmp x1, #ID_AA64ISAR1_EL1_LS64_LS64_V
- b.lt .Lset_hcrx_@
- orr x0, x0, #HCRX_EL2_EnASR
How do these HCRX settings survive a world-switch to and from a KVM guest? AFAICT, the trap deactivation path there restores HCRX_HOST_FLAGS when returning to the host. That would mean that the GCS code is broken too, unless I'm missing something :/
Will