Now that required functionality for GCS is in place expose
ID_AA64PFR1_EL1.GCS, allowing guests to be given the feature.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kvm/nested.c   | 7 ++++---
 arch/arm64/kvm/sys_regs.c | 2 --
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index 153b3e11b115..d2d55e18c610 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -1459,9 +1459,10 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val)
 
 	case SYS_ID_AA64PFR1_EL1:
 		/* Only support BTI, SSBS, CSV2_frac */
-		val &= (ID_AA64PFR1_EL1_BT	|
-			ID_AA64PFR1_EL1_SSBS	|
-			ID_AA64PFR1_EL1_CSV2_frac);
+		val &= (ID_AA64PFR1_EL1_BT		|
+			ID_AA64PFR1_EL1_SSBS		|
+			ID_AA64PFR1_EL1_CSV2_frac	|
+			ID_AA64PFR1_EL1_GCS);
 		break;
 
 	case SYS_ID_AA64MMFR0_EL1:
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 03fb2dce0b80..60e234422064 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1616,7 +1616,6 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX);
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR);
@@ -2953,7 +2952,6 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 				     ~(ID_AA64PFR1_EL1_PFAR |
 				       ID_AA64PFR1_EL1_MTEX |
 				       ID_AA64PFR1_EL1_THE |
-				       ID_AA64PFR1_EL1_GCS |
 				       ID_AA64PFR1_EL1_MTE_frac |
 				       ID_AA64PFR1_EL1_NMI |
 				       ID_AA64PFR1_EL1_RNDR_trap |

-- 
2.47.2

On Fri, 12 Sep 2025 10:25:31 +0100,
Mark Brown <broonie@kernel.org> wrote:
> 
> Now that required functionality for GCS is in place expose
> ID_AA64PFR1_EL1.GCS, allowing guests to be given the feature.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  arch/arm64/kvm/nested.c   | 7 ++++---
>  arch/arm64/kvm/sys_regs.c | 2 --
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
> index 153b3e11b115..d2d55e18c610 100644
> --- a/arch/arm64/kvm/nested.c
> +++ b/arch/arm64/kvm/nested.c
> @@ -1459,9 +1459,10 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val)
>  
>  	case SYS_ID_AA64PFR1_EL1:
>  		/* Only support BTI, SSBS, CSV2_frac */
> -		val &= (ID_AA64PFR1_EL1_BT	|
> -			ID_AA64PFR1_EL1_SSBS	|
> -			ID_AA64PFR1_EL1_CSV2_frac);
> +		val &= (ID_AA64PFR1_EL1_BT		|
> +			ID_AA64PFR1_EL1_SSBS		|
> +			ID_AA64PFR1_EL1_CSV2_frac	|
> +			ID_AA64PFR1_EL1_GCS);

How about updating the comment?

	M.

-- 
Jazz isn't dead. It just smells funny.