x86/mm: Abstract switching CR3

In preparation to adding additional PCID flushing, abstract the
loading of a new ASID into CR3.

[ PeterZ: Split out from big combo patch ]

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 254c9eb79fe5e7b6e8fbea070033f2706f5bd313..42a8875f73fec98973a8067355deebb09f987793 100644 (file)
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -100,6 +100,24 @@ static void choose_new_asid(struct mm_struct *next, u64 next_tlb_gen,
        *need_flush = true;
 }
 
+static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, bool need_flush)
+{
+       unsigned long new_mm_cr3;
+
+       if (need_flush) {
+               new_mm_cr3 = build_cr3(pgdir, new_asid);
+       } else {
+               new_mm_cr3 = build_cr3_noflush(pgdir, new_asid);
+       }
+
+       /*
+        * Caution: many callers of this function expect
+        * that load_cr3() is serializing and orders TLB
+        * fills with respect to the mm_cpumask writes.
+        */
+       write_cr3(new_mm_cr3);
+}
+
 void leave_mm(int cpu)
 {
        struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
@@ -230,7 +248,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
                if (need_flush) {
                        this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
                        this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
-                       write_cr3(build_cr3(next->pgd, new_asid));
+                       load_new_mm_cr3(next->pgd, new_asid, true);
 
                        /*
                         * NB: This gets called via leave_mm() in the idle path
@@ -243,7 +261,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
                        trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
                } else {
                        /* The new ASID is already up to date. */
-                       write_cr3(build_cr3_noflush(next->pgd, new_asid));
+                       load_new_mm_cr3(next->pgd, new_asid, false);
 
                        /* See above wrt _rcuidle. */
                        trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);