KVM: arm64: Handle AArch32 SPSR_{irq,abt,und,fiq} as RAZ/WI

When trapping accesses from a NV guest that tries to access
SPSR_{irq,abt,und,fiq}, make sure we handle them as RAZ/WI,
as if AArch32 wasn't implemented.

This involves a bit of repainting to make the visibility
handler more generic.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231023095444.1587322-6-maz@kernel.orgSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/include/asm/sysreg.h

@@ -505,6 +505,10 @@
 #define SYS_SPSR_EL2			sys_reg(3, 4, 4, 0, 0)
 #define SYS_ELR_EL2			sys_reg(3, 4, 4, 0, 1)
 #define SYS_SP_EL1			sys_reg(3, 4, 4, 1, 0)
+#define SYS_SPSR_irq			sys_reg(3, 4, 4, 3, 0)
+#define SYS_SPSR_abt			sys_reg(3, 4, 4, 3, 1)
+#define SYS_SPSR_und			sys_reg(3, 4, 4, 3, 2)
+#define SYS_SPSR_fiq			sys_reg(3, 4, 4, 3, 3)
 #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
 #define SYS_AFSR0_EL2			sys_reg(3, 4, 5, 1, 0)
 #define SYS_AFSR1_EL2			sys_reg(3, 4, 5, 1, 1)

arch/arm64/kvm/sys_regs.c

@@ -1791,8 +1791,8 @@ static unsigned int el2_visibility(const struct kvm_vcpu *vcpu,
  * HCR_EL2.E2H==1, and only in the sysreg table for convenience of
  * handling traps. Given that, they are always hidden from userspace.
  */
-static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,
-				    const struct sys_reg_desc *rd)
+static unsigned int hidden_user_visibility(const struct kvm_vcpu *vcpu,
+					   const struct sys_reg_desc *rd)
 {
 	return REG_HIDDEN_USER;
 }
@@ -1803,7 +1803,7 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,
 	.reset = rst,				\
 	.reg = name##_EL1,			\
 	.val = v,				\
-	.visibility = elx2_visibility,		\
+	.visibility = hidden_user_visibility,	\
 }
 
 /*
@@ -2387,6 +2387,16 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	EL2_REG(ELR_EL2, access_rw, reset_val, 0),
 	{ SYS_DESC(SYS_SP_EL1), access_sp_el1},
 
+	/* AArch32 SPSR_* are RES0 if trapped from a NV guest */
+	{ SYS_DESC(SYS_SPSR_irq), .access = trap_raz_wi,
+	  .visibility = hidden_user_visibility },
+	{ SYS_DESC(SYS_SPSR_abt), .access = trap_raz_wi,
+	  .visibility = hidden_user_visibility },
+	{ SYS_DESC(SYS_SPSR_und), .access = trap_raz_wi,
+	  .visibility = hidden_user_visibility },
+	{ SYS_DESC(SYS_SPSR_fiq), .access = trap_raz_wi,
+	  .visibility = hidden_user_visibility },
+
 	{ SYS_DESC(SYS_IFSR32_EL2), trap_undef, reset_unknown, IFSR32_EL2 },
 	EL2_REG(AFSR0_EL2, access_rw, reset_val, 0),
 	EL2_REG(AFSR1_EL2, access_rw, reset_val, 0),