x86/paravirt: Drop {read,write}_cr8() hooks

There is a lot of infrastructure for functionality which is used
exclusively in __{save,restore}_processor_state() on the suspend/resume
path.

cr8 is an alias of APIC_TASKPRI, and APIC_TASKPRI is saved/restored by
lapic_{suspend,resume}().  Saving and restoring cr8 independently of the
rest of the Local APIC state isn't a clever thing to be doing.

Delete the suspend/resume cr8 handling, which shrinks the size of struct
saved_context, and allows for the removal of both PVOPS.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20190715151641.29210-1-andrew.cooper3@citrix.com

arch/x86/include/asm/paravirt.h

@@ -139,18 +139,6 @@ static inline void __write_cr4(unsigned long x)
 	PVOP_VCALL1(cpu.write_cr4, x);
 }
 
-#ifdef CONFIG_X86_64
-static inline unsigned long read_cr8(void)
-{
-	return PVOP_CALL0(unsigned long, cpu.read_cr8);
-}
-
-static inline void write_cr8(unsigned long x)
-{
-	PVOP_VCALL1(cpu.write_cr8, x);
-}
-#endif
-
 static inline void arch_safe_halt(void)
 {
 	PVOP_VCALL0(irq.safe_halt);

arch/x86/include/asm/paravirt_types.h

@@ -119,11 +119,6 @@ struct pv_cpu_ops {
 
 	void (*write_cr4)(unsigned long);
 
-#ifdef CONFIG_X86_64
-	unsigned long (*read_cr8)(void);
-	void (*write_cr8)(unsigned long);
-#endif
-
 	/* Segment descriptor handling */
 	void (*load_tr_desc)(void);
 	void (*load_gdt)(const struct desc_ptr *);

arch/x86/include/asm/special_insns.h

@@ -73,20 +73,6 @@ static inline unsigned long native_read_cr4(void)
 
 void native_write_cr4(unsigned long val);
 
-#ifdef CONFIG_X86_64
-static inline unsigned long native_read_cr8(void)
-{
-	unsigned long cr8;
-	asm volatile("movq %%cr8,%0" : "=r" (cr8));
-	return cr8;
-}
-
-static inline void native_write_cr8(unsigned long val)
-{
-	asm volatile("movq %0,%%cr8" :: "r" (val) : "memory");
-}
-#endif
-
 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 static inline u32 rdpkru(void)
 {
@@ -200,16 +186,6 @@ static inline void wbinvd(void)
 
 #ifdef CONFIG_X86_64
 
-static inline unsigned long read_cr8(void)
-{
-	return native_read_cr8();
-}
-
-static inline void write_cr8(unsigned long x)
-{
-	native_write_cr8(x);
-}
-
 static inline void load_gs_index(unsigned selector)
 {
 	native_load_gs_index(selector);

arch/x86/include/asm/suspend_64.h

@@ -34,7 +34,7 @@ struct saved_context {
 	 */
 	unsigned long kernelmode_gs_base, usermode_gs_base, fs_base;
 
-	unsigned long cr0, cr2, cr3, cr4, cr8;
+	unsigned long cr0, cr2, cr3, cr4;
 	u64 misc_enable;
 	bool misc_enable_saved;
 	struct saved_msrs saved_msrs;

arch/x86/kernel/asm-offsets_64.c

@@ -62,7 +62,6 @@ int main(void)
 	ENTRY(cr2);
 	ENTRY(cr3);
 	ENTRY(cr4);
-	ENTRY(cr8);
 	ENTRY(gdt_desc);
 	BLANK();
 #undef ENTRY

arch/x86/kernel/paravirt.c

@@ -311,10 +311,6 @@ struct paravirt_patch_template pv_ops = {
 	.cpu.read_cr0		= native_read_cr0,
 	.cpu.write_cr0		= native_write_cr0,
 	.cpu.write_cr4		= native_write_cr4,
-#ifdef CONFIG_X86_64
-	.cpu.read_cr8		= native_read_cr8,
-	.cpu.write_cr8		= native_write_cr8,
-#endif
 	.cpu.wbinvd		= native_wbinvd,
 	.cpu.read_msr		= native_read_msr,
 	.cpu.write_msr		= native_write_msr,

arch/x86/power/cpu.c

@@ -122,9 +122,6 @@ static void __save_processor_state(struct saved_context *ctxt)
 	ctxt->cr2 = read_cr2();
 	ctxt->cr3 = __read_cr3();
 	ctxt->cr4 = __read_cr4();
-#ifdef CONFIG_X86_64
-	ctxt->cr8 = read_cr8();
-#endif
 	ctxt->misc_enable_saved = !rdmsrl_safe(MSR_IA32_MISC_ENABLE,
 					       &ctxt->misc_enable);
 	msr_save_context(ctxt);
@@ -207,7 +204,6 @@ static void notrace __restore_processor_state(struct saved_context *ctxt)
 #else
 /* CONFIG X86_64 */
 	wrmsrl(MSR_EFER, ctxt->efer);
-	write_cr8(ctxt->cr8);
 	__write_cr4(ctxt->cr4);
 #endif
 	write_cr3(ctxt->cr3);

arch/x86/xen/enlighten_pv.c

@@ -877,16 +877,6 @@ static void xen_write_cr4(unsigned long cr4)
 
 	native_write_cr4(cr4);
 }
-#ifdef CONFIG_X86_64
-static inline unsigned long xen_read_cr8(void)
-{
-	return 0;
-}
-static inline void xen_write_cr8(unsigned long val)
-{
-	BUG_ON(val);
-}
-#endif
 
 static u64 xen_read_msr_safe(unsigned int msr, int *err)
 {
@@ -1023,11 +1013,6 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
 
 	.write_cr4 = xen_write_cr4,
 
-#ifdef CONFIG_X86_64
-	.read_cr8 = xen_read_cr8,
-	.write_cr8 = xen_write_cr8,
-#endif
-
 	.wbinvd = native_wbinvd,
 
 	.read_msr = xen_read_msr,