x86/mm: Remove hard-coded ASID limit checks

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / include / asm / tlbflush.h

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index ee7925adfb5720df01a97859f244c658c7ed2ee7..f88ccd3ae466f0ba378eb6ed5178a32fa201f030 100644 (file)
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -69,6 +69,22 @@ static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
        return atomic64_inc_return(&mm->context.tlb_gen);
 }
 
+/* There are 12 bits of space for ASIDS in CR3 */
+#define CR3_HW_ASID_BITS               12
+/*
+ * When enabled, PAGE_TABLE_ISOLATION consumes a single bit for
+ * user/kernel switches
+ */
+#define PTI_CONSUMED_ASID_BITS         0
+
+#define CR3_AVAIL_ASID_BITS (CR3_HW_ASID_BITS - PTI_CONSUMED_ASID_BITS)
+/*
+ * ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid.  -1 below to account
+ * for them being zero-based.  Another -1 is because ASID 0 is reserved for
+ * use by non-PCID-aware users.
+ */
+#define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_ASID_BITS) - 2)
+
 /*
  * If PCID is on, ASID-aware code paths put the ASID+1 into the PCID bits.
  * This serves two purposes.  It prevents a nasty situation in which
@@ -81,7 +97,7 @@ struct pgd_t;
 static inline unsigned long build_cr3(pgd_t *pgd, u16 asid)
 {
        if (static_cpu_has(X86_FEATURE_PCID)) {
-               VM_WARN_ON_ONCE(asid > 4094);
+               VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
                return __sme_pa(pgd) | (asid + 1);
        } else {
                VM_WARN_ON_ONCE(asid != 0);
@@ -91,7 +107,7 @@ static inline unsigned long build_cr3(pgd_t *pgd, u16 asid)
 
 static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
 {
-       VM_WARN_ON_ONCE(asid > 4094);
+       VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
        return __sme_pa(pgd) | (asid + 1) | CR3_NOFLUSH;
 }