UBUNTU: SAUCE: clocksource: hyper-v: Use InvariantTSC and enable TSC page for a TDX VM without paravisor

BugLink: https://bugs.launchpad.net/bugs/2052519

Will improve the patch and post to LKML.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Ian May <ian.may@canonical.com>
Acked-by: Marcelo Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

Author: dcui

arch/x86/entry/vdso/vma.c

@@ -17,6 +17,7 @@
 #include <linux/time_namespace.h>
 
 #include <asm/pvclock.h>
+#include <asm/mshyperv.h>
 #include <asm/vgtod.h>
 #include <asm/proto.h>
 #include <asm/vdso.h>
@@ -189,9 +190,13 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		}
 	} else if (sym_offset == image->sym_hvclock_page) {
 		pfn = hv_get_tsc_pfn();
-
-		if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
-			return vmf_insert_pfn(vma, vmf->address, pfn);
+		if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK)) {
+			if (ms_hyperv.paravisor_present)
+				return vmf_insert_pfn(vma, vmf->address, pfn);
+			else
+				return vmf_insert_pfn_prot(vma, vmf->address,
+					pfn, pgprot_decrypted(vma->vm_page_prot));
+		}
 	} else if (sym_offset == image->sym_timens_page) {
 		struct page *timens_page = find_timens_vvar_page(vma);
 

arch/x86/kernel/cpu/mshyperv.c

@@ -507,14 +507,6 @@ static void __init ms_hyperv_init_platform(void)
 			ms_hyperv.hints &= ~HV_X64_APIC_ACCESS_RECOMMENDED;
 
 			if (!ms_hyperv.paravisor_present) {
-				/*
-				 * Mark the Hyper-V TSC page feature as disabled
-				 * in a TDX VM without paravisor so that the
-				 * Invariant TSC, which is a better clocksource
-				 * anyway, is used instead.
-				 */
-				ms_hyperv.features &= ~HV_MSR_REFERENCE_TSC_AVAILABLE;
-
 				/*
 				 * The Invariant TSC is expected to be available
 				 * in a TDX VM without paravisor, but if not,

drivers/clocksource/hyperv_timer.c

@@ -22,6 +22,7 @@
 #include <linux/irq.h>
 #include <linux/acpi.h>
 #include <linux/hyperv.h>
+#include <linux/set_memory.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
@@ -404,8 +405,8 @@ static __always_inline u64 read_hv_clock_msr(void)
 
 static union {
 	struct ms_hyperv_tsc_page page;
-	u8 reserved[PAGE_SIZE];
-} tsc_pg __bss_decrypted __aligned(PAGE_SIZE);
+	u8 reserved[SZ_2M];
+} tsc_pg __bss_decrypted __aligned(SZ_2M);
 
 static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
 static unsigned long tsc_pfn;
@@ -546,6 +547,7 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock) {}
 static void __init hv_init_tsc_clocksource(void)
 {
 	union hv_reference_tsc_msr tsc_msr;
+	int ret;
 
 	/*
 	 * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly
@@ -565,6 +567,12 @@ static void __init hv_init_tsc_clocksource(void)
 
 	hv_read_reference_counter = read_hv_clock_tsc;
 
+	if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present) {
+		ret = set_memory_decrypted((unsigned long)tsc_page, SZ_2M/PAGE_SIZE);
+		BUG_ON(ret);
+		memset(tsc_page, 0, PAGE_SIZE);
+	}
+
 	/*
 	 * TSC page mapping works differently in root compared to guest.
 	 * - In guest partition the guest PFN has to be passed to the
@@ -588,6 +596,10 @@ static void __init hv_init_tsc_clocksource(void)
 		tsc_pfn = HVPFN_DOWN(virt_to_phys(tsc_page));
 	tsc_msr.enable = 1;
 	tsc_msr.pfn = tsc_pfn;
+
+	if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
+		tsc_msr.pfn = PHYS_PFN(cc_mkdec(PFN_PHYS(tsc_msr.pfn)));
+
 	hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 
 	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);