From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
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.hansen@xxxxxxxxxxxxxxx>
Cc: Moritz Lipp <moritz.lipp@xxxxxxxxxxxxxx>
Cc: Daniel Gruss <daniel.gruss@xxxxxxxxxxxxxx>
Cc: Michael Schwarz <michael.schwarz@xxxxxxxxxxxxxx>
Cc: Richard Fellner <richard.fellner@xxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: x86@xxxxxxxxxx
---
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
_
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