[PATCH v12 16/29] KVM: arm64: Support TPIDR2_EL0

[Mark Brown]

SME adds a new thread ID register, TPIDR2_EL0. This is used in userspace
for delayed saving of the ZA state but in terms of the architecture is
not really connected to SME other than being part of FEAT_SME. It has an
independent fine grained trap and the runtime connection with the rest
of SME is purely software defined.

Expose the register as a system register if the guest supports SME,
context switching it along with the other EL0 TPIDRs.

Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 arch/arm64/include/asm/kvm_host.h          |  1 +
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 12 ++++++++++++
 arch/arm64/kvm/sys_regs.c                  |  6 +++++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 796b6e3a50f7..da7e572822a1 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -460,6 +460,7 @@ enum vcpu_sysreg {
 	CSSELR_EL1,	/* Cache Size Selection Register */
 	TPIDR_EL0,	/* Thread ID, User R/W */
 	TPIDRRO_EL0,	/* Thread ID, User R/O */
+	TPIDR2_EL0,	/* Thread ID, Register 2 */
 	TPIDR_EL1,	/* Thread ID, Privileged */
 	CNTKCTL_EL1,	/* Timer Control Register (EL1) */
 	PAR_EL1,	/* Physical Address Register */
diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
index 5624fd705ae3..0fd4092e4f25 100644
--- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
@@ -88,6 +88,14 @@ static inline bool ctxt_has_sctlr2(struct kvm_cpu_context *ctxt)
 	return kvm_has_sctlr2(kern_hyp_va(vcpu->kvm));
 }
 
+static inline bool ctxt_has_sme(struct kvm_cpu_context *ctxt)
+{
+	struct kvm_vcpu *vcpu;
+
+	vcpu = ctxt_to_vcpu(ctxt);
+	return kvm_has_sme(kern_hyp_va(vcpu->kvm));
+}
+
 static inline bool ctxt_is_guest(struct kvm_cpu_context *ctxt)
 {
 	return host_data_ptr(host_ctxt) != ctxt;
@@ -127,6 +135,8 @@ static inline void __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
 {
 	ctxt_sys_reg(ctxt, TPIDR_EL0)	= read_sysreg(tpidr_el0);
 	ctxt_sys_reg(ctxt, TPIDRRO_EL0)	= read_sysreg(tpidrro_el0);
+	if (ctxt_has_sme(ctxt))
+		ctxt_sys_reg(ctxt, TPIDR2_EL0)	= read_sysreg_s(SYS_TPIDR2_EL0);
 }
 
 static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
@@ -204,6 +214,8 @@ static inline void __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
 {
 	write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL0),	tpidr_el0);
 	write_sysreg(ctxt_sys_reg(ctxt, TPIDRRO_EL0),	tpidrro_el0);
+	if (ctxt_has_sme(ctxt))
+		write_sysreg_s(ctxt_sys_reg(ctxt, TPIDR2_EL0), SYS_TPIDR2_EL0);
 }
 
 static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt,
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 24bbe30c075a..8f19caac6008 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -131,6 +131,7 @@ static enum sr_loc_attr locate_direct_register(const struct kvm_vcpu *vcpu,
 
 	case TPIDR_EL0:
 	case TPIDRRO_EL0:
+	case TPIDR2_EL0:
 	case TPIDR_EL1:
 	case PAR_EL1:
 	case DACR32_EL2:
@@ -246,6 +247,7 @@ static u64 read_sr_from_cpu(enum vcpu_sysreg reg)
 	case SCTLR2_EL1:	val = read_sysreg_s(SYS_SCTLR2_EL12);	break;
 	case TPIDR_EL0:		val = read_sysreg_s(SYS_TPIDR_EL0);	break;
 	case TPIDRRO_EL0:	val = read_sysreg_s(SYS_TPIDRRO_EL0);	break;
+	case TPIDR2_EL0:	val = read_sysreg_s(SYS_TPIDR2_EL0);	break;
 	case TPIDR_EL1:		val = read_sysreg_s(SYS_TPIDR_EL1);	break;
 	case PAR_EL1:		val = read_sysreg_par();		break;
 	case DACR32_EL2:	val = read_sysreg_s(SYS_DACR32_EL2);	break;
@@ -285,6 +287,7 @@ static void write_sr_to_cpu(enum vcpu_sysreg reg, u64 val)
 	case SCTLR2_EL1:	write_sysreg_s(val, SYS_SCTLR2_EL12);	break;
 	case TPIDR_EL0:		write_sysreg_s(val, SYS_TPIDR_EL0);	break;
 	case TPIDRRO_EL0:	write_sysreg_s(val, SYS_TPIDRRO_EL0);	break;
+	case TPIDR2_EL0:	write_sysreg_s(val, SYS_TPIDR2_EL0);	break;
 	case TPIDR_EL1:		write_sysreg_s(val, SYS_TPIDR_EL1);	break;
 	case PAR_EL1:		write_sysreg_s(val, SYS_PAR_EL1);	break;
 	case DACR32_EL2:	write_sysreg_s(val, SYS_DACR32_EL2);	break;
@@ -3598,7 +3601,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  .visibility = s1poe_visibility },
 	{ SYS_DESC(SYS_TPIDR_EL0), NULL, reset_unknown, TPIDR_EL0 },
 	{ SYS_DESC(SYS_TPIDRRO_EL0), NULL, reset_unknown, TPIDRRO_EL0 },
-	{ SYS_DESC(SYS_TPIDR2_EL0), undef_access },
+	{ SYS_DESC(SYS_TPIDR2_EL0), NULL, reset_unknown, TPIDR2_EL0,
+	  .visibility = sme_visibility },
 
 	{ SYS_DESC(SYS_SCXTNUM_EL0), undef_access },
 

-- 
2.47.3