From: Dave Hansen <dave.han...@linux.intel.com> There are effectively two ASID types:
1. The one stored in the mmu_context that goes from 0..5 2. The one programmed into the hardware that goes from 1..6 This consolidates the locations where converting between the two (by doing a +1) to a single place which gives us a nice place to comment. PAGE_TABLE_ISOLATION will also need to, given an ASID, know which hardware ASID to flush for the userspace mapping. Signed-off-by: Dave Hansen <dave.han...@linux.intel.com> Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Andy Lutomirski <l...@kernel.org> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Dave Hansen <dave.han...@intel.com> Cc: David Laight <david.lai...@aculab.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Eduardo Valentin <edu...@amazon.com> Cc: Greg KH <gre...@linuxfoundation.org> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Juergen Gross <jgr...@suse.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Will Deacon <will.dea...@arm.com> Cc: aligu...@amazon.com Cc: daniel.gr...@iaik.tugraz.at Cc: hu...@google.com Cc: keesc...@google.com Cc: linux...@kvack.org --- arch/x86/include/asm/tlbflush.h | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -85,20 +85,26 @@ static inline u64 inc_mm_tlb_gen(struct */ #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 - * PCID-unaware code saves CR3, loads some other value (with PCID == 0), - * and then restores CR3, thus corrupting the TLB for ASID 0 if the saved - * ASID was nonzero. It also means that any bugs involving loading a - * PCID-enabled CR3 with CR4.PCIDE off will trigger deterministically. - */ +static inline u16 kern_pcid(u16 asid) +{ + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); + /* + * 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 PCID-unaware code saves CR3, loads some other + * value (with PCID == 0), and then restores CR3, thus corrupting + * the TLB for ASID 0 if the saved ASID was nonzero. It also means + * that any bugs involving loading a PCID-enabled CR3 with + * CR4.PCIDE off will trigger deterministically. + */ + return asid + 1; +} + 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 > MAX_ASID_AVAILABLE); - return __sme_pa(pgd) | (asid + 1); + return __sme_pa(pgd) | kern_pcid(asid); } else { VM_WARN_ON_ONCE(asid != 0); return __sme_pa(pgd); @@ -108,7 +114,8 @@ static inline unsigned long build_cr3(pg static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid) { VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); - return __sme_pa(pgd) | (asid + 1) | CR3_NOFLUSH; + VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID)); + return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH; } #ifdef CONFIG_PARAVIRT