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Date: Wed, 22 Jun 2022 19:22:26 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org, Kostya Serebryany <kcc@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
"H . J . Lu" <hjl.tools@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv4 4/8] x86/mm: Handle LAM on context switch
Linear Address Masking mode for userspace pointers encoded in CR3 bits.
The mode is selected per-thread. Add new thread features indicate that the
thread has Linear Address Masking enabled.
switch_mm_irqs_off() now respects these flags and constructs CR3
accordingly.
The active LAM mode gets recorded in the tlb_state.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
arch/x86/include/asm/mmu.h | 1 +
arch/x86/include/asm/mmu_context.h | 24 +++++++++++
arch/x86/include/asm/tlbflush.h | 4 ++
arch/x86/mm/tlb.c | 68 +++++++++++++++++++++++-------
4 files changed, 82 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 5d7494631ea9..d150e92163b6 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -40,6 +40,7 @@ typedef struct {
#ifdef CONFIG_X86_64
unsigned short flags;
+ u64 lam_cr3_mask;
#endif
struct mutex lock;
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index b8d40ddeab00..e6eac047c728 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -91,6 +91,29 @@ static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
}
#endif
+#ifdef CONFIG_X86_64
+static inline u64 mm_cr3_lam_mask(struct mm_struct *mm)
+{
+ return mm->context.lam_cr3_mask;
+}
+
+static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ mm->context.lam_cr3_mask = oldmm->context.lam_cr3_mask;
+}
+
+#else
+
+static inline u64 mm_cr3_lam_mask(struct mm_struct *mm)
+{
+ return 0;
+}
+
+static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+}
+#endif
+
#define enter_lazy_tlb enter_lazy_tlb
extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
@@ -168,6 +191,7 @@ static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
{
arch_dup_pkeys(oldmm, mm);
paravirt_arch_dup_mmap(oldmm, mm);
+ dup_lam(oldmm, mm);
return ldt_dup_context(oldmm, mm);
}
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 4af5579c7ef7..2d70d75e207f 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -100,6 +100,10 @@ struct tlb_state {
*/
bool invalidate_other;
+#ifdef CONFIG_X86_64
+ u8 lam;
+#endif
+
/*
* Mask that contains TLB_NR_DYN_ASIDS+1 bits to indicate
* the corresponding user PCID needs a flush next time we
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index d400b6d9d246..c5c4f76329c2 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -154,17 +154,17 @@ static inline u16 user_pcid(u16 asid)
return ret;
}
-static inline unsigned long build_cr3(pgd_t *pgd, u16 asid)
+static inline unsigned long build_cr3(pgd_t *pgd, u16 asid, u64 lam)
{
if (static_cpu_has(X86_FEATURE_PCID)) {
- return __sme_pa(pgd) | kern_pcid(asid);
+ return __sme_pa(pgd) | kern_pcid(asid) | lam;
} else {
VM_WARN_ON_ONCE(asid != 0);
- return __sme_pa(pgd);
+ return __sme_pa(pgd) | lam;
}
}
-static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
+static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid, u64 lam)
{
VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
/*
@@ -173,7 +173,7 @@ static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
* boot because all CPU's the have same capabilities:
*/
VM_WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_PCID));
- return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH;
+ return __sme_pa(pgd) | kern_pcid(asid) | lam | CR3_NOFLUSH;
}
/*
@@ -274,15 +274,15 @@ static inline void invalidate_user_asid(u16 asid)
(unsigned long *)this_cpu_ptr(&cpu_tlbstate.user_pcid_flush_mask));
}
-static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, bool need_flush)
+static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, u64 lam, bool need_flush)
{
unsigned long new_mm_cr3;
if (need_flush) {
invalidate_user_asid(new_asid);
- new_mm_cr3 = build_cr3(pgdir, new_asid);
+ new_mm_cr3 = build_cr3(pgdir, new_asid, lam);
} else {
- new_mm_cr3 = build_cr3_noflush(pgdir, new_asid);
+ new_mm_cr3 = build_cr3_noflush(pgdir, new_asid, lam);
}
/*
@@ -486,11 +486,38 @@ void cr4_update_pce(void *ignored)
static inline void cr4_update_pce_mm(struct mm_struct *mm) { }
#endif
+#ifdef CONFIG_X86_64
+static inline u64 tlbstate_lam_cr3_mask(void)
+{
+ u64 lam = this_cpu_read(cpu_tlbstate.lam);
+
+ return lam << X86_CR3_LAM_U57_BIT;
+}
+
+static inline void set_tlbstate_lam_cr3_mask(u64 mask)
+{
+ this_cpu_write(cpu_tlbstate.lam, mask >> X86_CR3_LAM_U57_BIT);
+}
+
+#else
+
+static inline u64 tlbstate_lam_cr3_mask(void)
+{
+ return 0;
+}
+
+static inline void set_tlbstate_lam_cr3_mask(u64 mask)
+{
+}
+#endif
+
void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm);
u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
+ u64 prev_lam = tlbstate_lam_cr3_mask();
+ u64 new_lam = mm_cr3_lam_mask(next);
bool was_lazy = this_cpu_read(cpu_tlbstate_shared.is_lazy);
unsigned cpu = smp_processor_id();
u64 next_tlb_gen;
@@ -504,6 +531,9 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
* cpu_tlbstate.loaded_mm) matches next.
*
* NB: leave_mm() calls us with prev == NULL and tsk == NULL.
+ *
+ * NB: Initial LAM enabling calls us with prev == next. We must update
+ * CR3 if prev_lam doesn't match the new one.
*/
/* We don't want flush_tlb_func() to run concurrently with us. */
@@ -520,7 +550,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
* isn't free.
*/
#ifdef CONFIG_DEBUG_VM
- if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev->pgd, prev_asid))) {
+ if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev->pgd, prev_asid, prev_lam))) {
/*
* If we were to BUG here, we'd be very likely to kill
* the system so hard that we don't see the call trace.
@@ -551,7 +581,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
* provides that full memory barrier and core serializing
* instruction.
*/
- if (real_prev == next) {
+ if (real_prev == next && prev_lam == new_lam) {
VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) !=
next->context.ctx_id);
@@ -622,15 +652,16 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
barrier();
}
+ set_tlbstate_lam_cr3_mask(new_lam);
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);
- load_new_mm_cr3(next->pgd, new_asid, true);
+ load_new_mm_cr3(next->pgd, new_asid, new_lam, true);
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
} else {
/* The new ASID is already up to date. */
- load_new_mm_cr3(next->pgd, new_asid, false);
+ load_new_mm_cr3(next->pgd, new_asid, new_lam, false);
trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, 0);
}
@@ -691,6 +722,10 @@ void initialize_tlbstate_and_flush(void)
/* Assert that CR3 already references the right mm. */
WARN_ON((cr3 & CR3_ADDR_MASK) != __pa(mm->pgd));
+ /* LAM expected to be disabled in CR3 and init_mm */
+ WARN_ON(cr3 & (X86_CR3_LAM_U48 | X86_CR3_LAM_U57));
+ WARN_ON(mm_cr3_lam_mask(&init_mm));
+
/*
* Assert that CR4.PCIDE is set if needed. (CR4.PCIDE initialization
* doesn't work like other CR4 bits because it can only be set from
@@ -700,7 +735,7 @@ void initialize_tlbstate_and_flush(void)
!(cr4_read_shadow() & X86_CR4_PCIDE));
/* Force ASID 0 and force a TLB flush. */
- write_cr3(build_cr3(mm->pgd, 0));
+ write_cr3(build_cr3(mm->pgd, 0, 0));
/* Reinitialize tlbstate. */
this_cpu_write(cpu_tlbstate.last_user_mm_spec, LAST_USER_MM_INIT);
@@ -708,6 +743,7 @@ void initialize_tlbstate_and_flush(void)
this_cpu_write(cpu_tlbstate.next_asid, 1);
this_cpu_write(cpu_tlbstate.ctxs[0].ctx_id, mm->context.ctx_id);
this_cpu_write(cpu_tlbstate.ctxs[0].tlb_gen, tlb_gen);
+ set_tlbstate_lam_cr3_mask(0);
for (i = 1; i < TLB_NR_DYN_ASIDS; i++)
this_cpu_write(cpu_tlbstate.ctxs[i].ctx_id, 0);
@@ -1047,8 +1083,10 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
*/
unsigned long __get_current_cr3_fast(void)
{
- unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
- this_cpu_read(cpu_tlbstate.loaded_mm_asid));
+ unsigned long cr3 =
+ build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd,
+ this_cpu_read(cpu_tlbstate.loaded_mm_asid),
+ tlbstate_lam_cr3_mask());
/* For now, be very restrictive about when this can be called. */
VM_WARN_ON(in_nmi() || preemptible());
--
2.35.1
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