clocksource: hyper-v: Mark hyperv tsc page unencrypted in sev-snp enlightened guest

Hyper-V tsc page is shared with hypervisor and mark the page
unencrypted in sev-snp enlightened guest when it's used.

Reviewed-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-7-ltykernel@gmail.com

Author: tiala

drivers/clocksource/hyperv_timer.c

@@ -390,7 +390,7 @@ static __always_inline u64 read_hv_clock_msr(void)
 static union {
 	struct ms_hyperv_tsc_page page;
 	u8 reserved[PAGE_SIZE];
-} tsc_pg __aligned(PAGE_SIZE);
+} tsc_pg __bss_decrypted __aligned(PAGE_SIZE);
 
 static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
 static unsigned long tsc_pfn;