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 beween the two (by doing +1) to a single place which gives us a nice place to comment. KAISER 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> Cc: Moritz Lipp <moritz.l...@iaik.tugraz.at> Cc: Daniel Gruss <daniel.gr...@iaik.tugraz.at> Cc: Michael Schwarz <michael.schw...@iaik.tugraz.at> Cc: Richard Fellner <richard.fell...@student.tugraz.at> Cc: Andy Lutomirski <l...@kernel.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Kees Cook <keesc...@google.com> Cc: Hugh Dickins <hu...@google.com> Cc: x...@kernel.org --- b/arch/x86/include/asm/tlbflush.h | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff -puN arch/x86/include/asm/tlbflush.h~kaiser-pcid-pre-build-kern arch/x86/include/asm/tlbflush.h --- a/arch/x86/include/asm/tlbflush.h~kaiser-pcid-pre-build-kern 2017-11-22 15:45:52.346619731 -0800 +++ b/arch/x86/include/asm/tlbflush.h 2017-11-22 15:45:52.350619731 -0800 @@ -88,21 +88,26 @@ 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_asid(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_asid(asid); } else { VM_WARN_ON_ONCE(asid != 0); return __sme_pa(pgd); @@ -112,7 +117,8 @@ 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_asid(asid) | CR3_NOFLUSH; } #ifdef CONFIG_PARAVIRT _