KVM: arm64: Handle 32bit CNTPCTSS traps

When CNTPOFF isn't implemented and that we have a non-zero counter
offset, CNTPCT and CNTPCTSS are trapped. We properly handle the
former, but not the latter, as it is not present in the sysreg
table (despite being actually handled in the code). Bummer.

Just populate the cp15_64 table with the missing register.
Reported-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/sysreg.h

@@ -403,6 +403,7 @@
 #define SYS_AARCH32_CNTP_CTL		sys_reg(0, 0, 14, 2, 1)
 #define SYS_AARCH32_CNTPCT		sys_reg(0, 0, 0, 14, 0)
 #define SYS_AARCH32_CNTP_CVAL		sys_reg(0, 2, 0, 14, 0)
+#define SYS_AARCH32_CNTPCTSS		sys_reg(0, 8, 0, 14, 0)
 
 #define __PMEV_op2(n)			((n) & 0x7)
 #define __CNTR_CRm(n)			(0x8 | (((n) >> 3) & 0x3))

arch/arm64/kvm/sys_regs.c

@@ -2538,6 +2538,7 @@ static const struct sys_reg_desc cp15_64_regs[] = {
 	{ Op1( 1), CRn( 0), CRm(12), Op2( 0), access_gic_sgi }, /* ICC_ASGI1R */
 	{ Op1( 2), CRn( 0), CRm(12), Op2( 0), access_gic_sgi }, /* ICC_SGI0R */
 	{ SYS_DESC(SYS_AARCH32_CNTP_CVAL),    access_arch_timer },
+	{ SYS_DESC(SYS_AARCH32_CNTPCTSS),     access_arch_timer },
 };
 
 static bool check_sysreg_table(const struct sys_reg_desc *table, unsigned int n,