Re: [PATCH v3 3/6] KVM: arm64: Allow guest to set the OSLK bit

Allow writes to OSLAR and forward the OSLK bit to OSLSR. Do nothing with
the value for now.

Reviewed-by: Reiji Watanabe <redacted>
Signed-off-by: Oliver Upton <redacted>
---
 arch/arm64/include/asm/sysreg.h |  6 ++++++
 arch/arm64/kvm/sys_regs.c       | 33 ++++++++++++++++++++++++++-------
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 16b3f1a1d468..9fad61a82047 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h

@@ -129,7 +129,13 @@
 #define SYS_DBGWCRn_EL1(n)		sys_reg(2, 0, 0, n, 7)
 #define SYS_MDRAR_EL1			sys_reg(2, 0, 1, 0, 0)
 #define SYS_OSLAR_EL1			sys_reg(2, 0, 1, 0, 4)
+
+#define SYS_OSLAR_OSLK			BIT(0)
+
 #define SYS_OSLSR_EL1			sys_reg(2, 0, 1, 1, 4)
+
+#define SYS_OSLSR_OSLK			BIT(1)
+
 #define SYS_OSDLR_EL1			sys_reg(2, 0, 1, 3, 4)
 #define SYS_DBGPRCR_EL1			sys_reg(2, 0, 1, 4, 4)
 #define SYS_DBGCLAIMSET_EL1		sys_reg(2, 0, 7, 8, 6)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 7bf350b3d9cd..5dbdb45d6d44 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -44,6 +44,10 @@
  * 64bit interface.
  */
 
+static int reg_from_user(u64 *val, const void __user *uaddr, u64 id);
+static int reg_to_user(void __user *uaddr, const u64 *val, u64 id);
+static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
+
 static bool read_from_write_only(struct kvm_vcpu *vcpu,
 				 struct sys_reg_params *params,
 				 const struct sys_reg_desc *r)

@@ -287,6 +291,24 @@ static bool trap_loregion(struct kvm_vcpu *vcpu,
 	return trap_raz_wi(vcpu, p, r);
 }
 
+static bool trap_oslar_el1(struct kvm_vcpu *vcpu,
+			   struct sys_reg_params *p,
+			   const struct sys_reg_desc *r)
+{
+	u64 oslsr;
+
+	if (!p->is_write)
+		return read_from_write_only(vcpu, p, r);
+
+	/* Forward the OSLK bit to OSLSR */
+	oslsr = __vcpu_sys_reg(vcpu, OSLSR_EL1) & ~SYS_OSLSR_OSLK;
+	if (p->regval & SYS_OSLAR_OSLK)
+		oslsr |= SYS_OSLSR_OSLK;
+
+	__vcpu_sys_reg(vcpu, OSLSR_EL1) = oslsr;
+	return true;
+}
+
 static bool trap_oslsr_el1(struct kvm_vcpu *vcpu,
 			   struct sys_reg_params *p,
 			   const struct sys_reg_desc *r)

@@ -309,9 +331,10 @@ static int set_oslsr_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 	if (err)
 		return err;
 
-	if (val != rd->val)
+	if ((val & ~SYS_OSLSR_OSLK) != rd->val)
 		return -EINVAL;