clocksource: hyper-v: Use TSC PFN getter to map vvar page

Instead of converting the virtual address to physical directly.

This is a precursor patch for the upcoming support for TSC page mapping into
Microsoft Hypervisor root partition, where TSC PFN will be defined by the
hypervisor and thus can't be obtained by linear translation of the physical
address.

Signed-off-by: Stanislav Kinsburskiy <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Thomas Gleixner <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Borislav Petkov <[email protected]>
CC: Dave Hansen <[email protected]>
CC: [email protected]
CC: "H. Peter Anvin" <[email protected]>
CC: "K. Y. Srinivasan" <[email protected]>
CC: Haiyang Zhang <[email protected]>
CC: Wei Liu <[email protected]>
CC: Dexuan Cui <[email protected]>
CC: Daniel Lezcano <[email protected]>
CC: [email protected]
CC: [email protected]
Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Anirudh Rayabharam <[email protected]>
Link: https://lore.kernel.org/r/166749833939.218190.14095015146003109462.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net
Signed-off-by: Wei Liu <[email protected]>

3 files changed, 11 insertions, 5 deletions

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 311eae30e089..6976416b2c9f 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -210,11 +210,10 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 					pgprot_decrypted(vma->vm_page_prot));
 		}
 	} else if (sym_offset == image->sym_hvclock_page) {
-		struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
+		pfn = hv_get_tsc_pfn();
 
-		if (tsc_pg && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
-			return vmf_insert_pfn(vma, vmf->address,
-					virt_to_phys(tsc_pg) >> PAGE_SHIFT);
+		if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
+			return vmf_insert_pfn(vma, vmf->address, pfn);
 	} else if (sym_offset == image->sym_timens_page) {
 		struct page *timens_page = find_timens_vvar_page(vma);
 
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index b7af19d06b51..9445a1558fe9 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -370,10 +370,11 @@ static union {
 static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
 static unsigned long tsc_pfn;
 
-static unsigned long hv_get_tsc_pfn(void)
+unsigned long hv_get_tsc_pfn(void)
 {
 	return tsc_pfn;
 }
+EXPORT_SYMBOL_GPL(hv_get_tsc_pfn);
 
 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 {
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index b3f5d73ae1d6..3078d23faaea 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -32,6 +32,7 @@ extern void hv_stimer0_isr(void);
 
 extern void hv_init_clocksource(void);
 
+extern unsigned long hv_get_tsc_pfn(void);
 extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
 
 static inline notrace u64
@@ -90,6 +91,11 @@ hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
 }
 
 #else /* CONFIG_HYPERV_TIMER */
+static inline unsigned long hv_get_tsc_pfn(void)
+{
+	return 0;
+}
+
 static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 {
 	return NULL;