linux-kernel - [PATCH 4.14 61/68] x86/pvclock: add setter for pvclock_pvti_cpu0

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Date:   Tue, 29 Jan 2019 12:36:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joao Martins <joao.m.martins@...cle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>
Subject: [PATCH 4.14 61/68] x86/pvclock: add setter for pvclock_pvti_cpu0_va

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joao Martins <joao.m.martins@...cle.com>

commit 9f08890ab906abaf9d4c1bad8111755cbd302260 upstream.

Right now there is only a pvclock_pvti_cpu0_va() which is defined
on kvmclock since:

commit dac16fba6fc5
("x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap")

The only user of this interface so far is kvm. This commit adds a
setter function for the pvti page and moves pvclock_pvti_cpu0_va
to pvclock, which is a more generic place to have it; and would
allow other PV clocksources to use it, such as Xen.

While moving pvclock_pvti_cpu0_va into pvclock, rename also this
function to pvclock_get_pvti_cpu0_va (including its call sites)
to be symmetric with the setter (pvclock_set_pvti_cpu0_va).

Signed-off-by: Joao Martins <joao.m.martins@...cle.com>
Acked-by: Andy Lutomirski <luto@...nel.org>
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/entry/vdso/vma.c      |    2 +-
 arch/x86/include/asm/pvclock.h |   19 ++++++++++---------
 arch/x86/kernel/kvmclock.c     |    7 +------
 arch/x86/kernel/pvclock.c      |   14 ++++++++++++++
 drivers/ptp/ptp_kvm.c          |    2 +-
 5 files changed, 27 insertions(+), 17 deletions(-)

--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -112,7 +112,7 @@ static int vvar_fault(const struct vm_sp
 				    __pa_symbol(&__vvar_page) >> PAGE_SHIFT);
 	} else if (sym_offset == image->sym_pvclock_page) {
 		struct pvclock_vsyscall_time_info *pvti =
-			pvclock_pvti_cpu0_va();
+			pvclock_get_pvti_cpu0_va();
 		if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
 			ret = vm_insert_pfn(
 				vma,
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -5,15 +5,6 @@
 #include <linux/clocksource.h>
 #include <asm/pvclock-abi.h>
 
-#ifdef CONFIG_KVM_GUEST
-extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
-#else
-static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
-{
-	return NULL;
-}
-#endif
-
 /* some helper functions for xen and kvm pv clock sources */
 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
@@ -102,4 +93,14 @@ struct pvclock_vsyscall_time_info {
 
 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 
+#ifdef CONFIG_PARAVIRT_CLOCK
+void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
+struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void);
+#else
+static inline struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void)
+{
+	return NULL;
+}
+#endif
+
 #endif /* _ASM_X86_PVCLOCK_H */
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -47,12 +47,6 @@ early_param("no-kvmclock", parse_no_kvmc
 static struct pvclock_vsyscall_time_info *hv_clock;
 static struct pvclock_wall_clock wall_clock;
 
-struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
-{
-	return hv_clock;
-}
-EXPORT_SYMBOL_GPL(pvclock_pvti_cpu0_va);
-
 /*
  * The wallclock is the time of day when we booted. Since then, some time may
  * have elapsed since the hypervisor wrote the data. So we try to account for
@@ -335,6 +329,7 @@ int __init kvm_setup_vsyscall_timeinfo(v
 		return 1;
 	}
 
+	pvclock_set_pvti_cpu0_va(hv_clock);
 	put_cpu();
 
 	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -25,8 +25,10 @@
 
 #include <asm/fixmap.h>
 #include <asm/pvclock.h>
+#include <asm/vgtod.h>
 
 static u8 valid_flags __read_mostly = 0;
+static struct pvclock_vsyscall_time_info *pvti_cpu0_va __read_mostly;
 
 void pvclock_set_flags(u8 flags)
 {
@@ -144,3 +146,15 @@ void pvclock_read_wallclock(struct pvclo
 
 	set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
 }
+
+void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti)
+{
+	WARN_ON(vclock_was_used(VCLOCK_PVCLOCK));
+	pvti_cpu0_va = pvti;
+}
+
+struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void)
+{
+	return pvti_cpu0_va;
+}
+EXPORT_SYMBOL_GPL(pvclock_get_pvti_cpu0_va);
--- a/drivers/ptp/ptp_kvm.c
+++ b/drivers/ptp/ptp_kvm.c
@@ -182,7 +182,7 @@ static int __init ptp_kvm_init(void)
 		return -ENODEV;
 
 	clock_pair_gpa = slow_virt_to_phys(&clock_pair);
-	hv_clock = pvclock_pvti_cpu0_va();
+	hv_clock = pvclock_get_pvti_cpu0_va();
 
 	if (!hv_clock)
 		return -ENODEV;