[PATCH 03/17] x86/tsc/paravirt: Remove the read_tsc and read_tscp paravirt hooks

[Andy Lutomirski <luto@kernel.org>]

We've had read_tsc and read_tscp paravirt hooks since the very
beginning of paravirt, i.e., d3561b7fa0fb ("[PATCH] paravirt: header
and stubs for paravirtualisation").  AFAICT the only paravirt guest
implementation that ever replaced these calls was vmware, and it's
gone.  Arguably even vmware shouldn't have hooked rdtsc -- we fully
support systems that don't have a TSC at all, so there's no point
for a paravirt implementation to pretend that we have a TSC but to
replace it.

I also doubt that these hooks actually worked.  Calls to rdtscl and
rdtscll, which respected the hooks, were used seemingly
interchangeably with native_read_tsc, which did not.

Just remove them.  If anyone ever needs them again, they can try
to make a case for why they need them.

Before, on a paravirt config:
   text	   data	    bss	    dec	    hex	filename
13426505	1827056	14508032	29761593	1c62039	vmlinux

After:
   text	   data	    bss	    dec	    hex	filename
13426617	1827056	14508032	29761705	1c620a9	vmlinux

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/include/asm/msr.h            | 16 ++++++++--------
 arch/x86/include/asm/paravirt.h       | 34 ----------------------------------
 arch/x86/include/asm/paravirt_types.h |  2 --
 arch/x86/kernel/paravirt.c            |  2 --
 arch/x86/kernel/paravirt_patch_32.c   |  2 --
 arch/x86/xen/enlighten.c              |  3 ---
 6 files changed, 8 insertions(+), 51 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 88711470af7f..d1afac7df484 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -178,12 +178,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
 	return err;
 }
 
-#define rdtscl(low)						\
-	((low) = (u32)native_read_tsc())
-
-#define rdtscll(val)						\
-	((val) = native_read_tsc())
-
 #define rdpmc(counter, low, high)			\
 do {							\
 	u64 _l = native_read_pmc((counter));		\
@@ -193,6 +187,14 @@ do {							\
 
 #define rdpmcl(counter, val) ((val) = native_read_pmc(counter))
 
+#endif	/* !CONFIG_PARAVIRT */
+
+#define rdtscl(low)						\
+	((low) = (u32)native_read_tsc())
+
+#define rdtscll(val)						\
+	((val) = native_read_tsc())
+
 #define rdtscp(low, high, aux)					\
 do {                                                            \
 	unsigned long long _val = native_read_tscp(&(aux));     \
@@ -202,8 +204,6 @@ do {                                                            \
 
 #define rdtscpll(val, aux) (val) = native_read_tscp(&(aux))
 
-#endif	/* !CONFIG_PARAVIRT */
-
 /*
  * 64-bit version of wrmsr_safe():
  */
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index d143bfad45d7..c2be0375bcad 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -174,19 +174,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
 	return err;
 }
 
-static inline u64 paravirt_read_tsc(void)
-{
-	return PVOP_CALL0(u64, pv_cpu_ops.read_tsc);
-}
-
-#define rdtscl(low)				\
-do {						\
-	u64 _l = paravirt_read_tsc();		\
-	low = (int)_l;				\
-} while (0)
-
-#define rdtscll(val) (val = paravirt_read_tsc())
-
 static inline unsigned long long paravirt_sched_clock(void)
 {
 	return PVOP_CALL0(unsigned long long, pv_time_ops.sched_clock);
@@ -215,27 +202,6 @@ do {						\
 
 #define rdpmcl(counter, val) ((val) = paravirt_read_pmc(counter))
 
-static inline unsigned long long paravirt_rdtscp(unsigned int *aux)
-{
-	return PVOP_CALL1(u64, pv_cpu_ops.read_tscp, aux);
-}
-
-#define rdtscp(low, high, aux)				\
-do {							\
-	int __aux;					\
-	unsigned long __val = paravirt_rdtscp(&__aux);	\
-	(low) = (u32)__val;				\
-	(high) = (u32)(__val >> 32);			\
-	(aux) = __aux;					\
-} while (0)
-
-#define rdtscpll(val, aux)				\
-do {							\
-	unsigned long __aux; 				\
-	val = paravirt_rdtscp(&__aux);			\
-	(aux) = __aux;					\
-} while (0)
-
 static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
 {
 	PVOP_VCALL2(pv_cpu_ops.alloc_ldt, ldt, entries);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index a6b8f9fadb06..ce029e4fa7c6 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -156,9 +156,7 @@ struct pv_cpu_ops {
 	u64 (*read_msr)(unsigned int msr, int *err);
 	int (*write_msr)(unsigned int msr, unsigned low, unsigned high);
 
-	u64 (*read_tsc)(void);
 	u64 (*read_pmc)(int counter);
-	unsigned long long (*read_tscp)(unsigned int *aux);
 
 #ifdef CONFIG_X86_32
 	/*
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 58bcfb67c01f..f68e48f5f6c2 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -351,9 +351,7 @@ __visible struct pv_cpu_ops pv_cpu_ops = {
 	.wbinvd = native_wbinvd,
 	.read_msr = native_read_msr_safe,
 	.write_msr = native_write_msr_safe,
-	.read_tsc = native_read_tsc,
 	.read_pmc = native_read_pmc,
-	.read_tscp = native_read_tscp,
 	.load_tr_desc = native_load_tr_desc,
 	.set_ldt = native_set_ldt,
 	.load_gdt = native_load_gdt,
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index e1b013696dde..c89f50a76e97 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -10,7 +10,6 @@ DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
 DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
 DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
 DEF_NATIVE(pv_cpu_ops, clts, "clts");
-DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc");
 
 #if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
 DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
@@ -52,7 +51,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
 		PATCH_SITE(pv_mmu_ops, read_cr3);
 		PATCH_SITE(pv_mmu_ops, write_cr3);
 		PATCH_SITE(pv_cpu_ops, clts);
-		PATCH_SITE(pv_cpu_ops, read_tsc);
 #if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
 		case PARAVIRT_PATCH(pv_lock_ops.queued_spin_unlock):
 			if (pv_is_native_spin_unlock()) {
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 0b95c9b8283f..32136bfca43f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1175,11 +1175,8 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
 	.read_msr = xen_read_msr_safe,
 	.write_msr = xen_write_msr_safe,
 
-	.read_tsc = native_read_tsc,
 	.read_pmc = native_read_pmc,
 
-	.read_tscp = native_read_tscp,
-
 	.iret = xen_iret,
 #ifdef CONFIG_X86_64
 	.usergs_sysret32 = xen_sysret32,
-- 
2.4.2