KVM: arm64: Introduce handling of AArch32 TTBCR2 traps

ARMv8.2 introduced TTBCR2, which shares TCR_EL1 with TTBCR.
Gracefully handle traps to this register when HCR_EL2.TVM is set.

Cc: stable@vger.kernel.org
Reported-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_host.h

@@ -212,6 +212,7 @@ enum vcpu_sysreg {
 #define c2_TTBR1	(TTBR1_EL1 * 2)	/* Translation Table Base Register 1 */
 #define c2_TTBR1_high	(c2_TTBR1 + 1)	/* TTBR1 top 32 bits */
 #define c2_TTBCR	(TCR_EL1 * 2)	/* Translation Table Base Control R. */
+#define c2_TTBCR2	(c2_TTBCR + 1)	/* Translation Table Base Control R. 2 */
 #define c3_DACR		(DACR32_EL2 * 2)/* Domain Access Control Register */
 #define c5_DFSR		(ESR_EL1 * 2)	/* Data Fault Status Register */
 #define c5_IFSR		(IFSR32_EL2 * 2)/* Instruction Fault Status Register */

arch/arm64/kvm/sys_regs.c

@@ -1925,6 +1925,7 @@ static const struct sys_reg_desc cp15_regs[] = {
 	{ Op1( 0), CRn( 2), CRm( 0), Op2( 0), access_vm_reg, NULL, c2_TTBR0 },
 	{ Op1( 0), CRn( 2), CRm( 0), Op2( 1), access_vm_reg, NULL, c2_TTBR1 },
 	{ Op1( 0), CRn( 2), CRm( 0), Op2( 2), access_vm_reg, NULL, c2_TTBCR },
+	{ Op1( 0), CRn( 2), CRm( 0), Op2( 3), access_vm_reg, NULL, c2_TTBCR2 },
 	{ Op1( 0), CRn( 3), CRm( 0), Op2( 0), access_vm_reg, NULL, c3_DACR },
 	{ Op1( 0), CRn( 5), CRm( 0), Op2( 0), access_vm_reg, NULL, c5_DFSR },
 	{ Op1( 0), CRn( 5), CRm( 0), Op2( 1), access_vm_reg, NULL, c5_IFSR },