[PATCH v9 05/12] x86/mm: add INVLPGB support code

Rik van Riel
2025-02-06T04:44:14Z

Add invlpgb.h with the helper functions and definitions needed to use
broadcast TLB invalidation on AMD EPYC 3 and newer CPUs.

Signed-off-by: Rik van Riel <riel@surriel.com>
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
---
arch/x86/include/asm/invlpgb.h | 101 ++++++++++++++++++++++++++++++++
arch/x86/include/asm/tlbflush.h | 1 +
2 files changed, 102 insertions(+)
create mode 100644 arch/x86/include/asm/invlpgb.h

diff --git a/arch/x86/include/asm/invlpgb.h b/arch/x86/include/asm/invlpgb.h
new file mode 100644
index 000000000000..a1d5dedd5217
--- /dev/null
+++ b/arch/x86/include/asm/invlpgb.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_INVLPGB
+#define _ASM_X86_INVLPGB
+
+#include <linux/kernel.h>
+#include <vdso/bits.h>
+#include <vdso/page.h>
+
+/*
+ * INVLPGB does broadcast TLB invalidation across all the CPUs in the system.
+ *
+ * The INVLPGB instruction is weakly ordered, and a batch of invalidations can
+ * be done in a parallel fashion.
+ *
+ * TLBSYNC is used to ensure that pending INVLPGB invalidations initiated from
+ * this CPU have completed.
+ */
+static inline void __invlpgb(unsigned long asid, unsigned long pcid,
+ unsigned long addr, u16 extra_count,
+ bool pmd_stride, u8 flags)
+{
+ u32 edx = (pcid << 16) | asid;
+ u32 ecx = (pmd_stride << 31) | extra_count;
+ u64 rax = addr | flags;
+
+ /* The low bits in rax are for flags. Verify addr is clean. */
+ VM_WARN_ON_ONCE(addr & ~PAGE_MASK);
+
+ /* INVLPGB; supported in binutils >= 2.36. */
+ asm volatile(".byte 0x0f, 0x01, 0xfe" : : "a" (rax), "c" (ecx), "d" (edx));
+}
+
+/* Wait for INVLPGB originated by this CPU to complete. */
+static inline void tlbsync(void)
+{
+ cant_migrate();
+ /* TLBSYNC: supported in binutils >= 0.36. */
+ asm volatile(".byte 0x0f, 0x01, 0xff" ::: "memory");
+}
+
+/*
+ * INVLPGB can be targeted by virtual address, PCID, ASID, or any combination
+ * of the three. For example:
+ * - INVLPGB_VA | INVLPGB_INCLUDE_GLOBAL: invalidate all TLB entries at the address
+ * - INVLPGB_PCID: invalidate all TLB entries matching the PCID
+ *
+ * The first can be used to invalidate (kernel) mappings at a particular
+ * address across all processes.
+ *
+ * The latter invalidates all TLB entries matching a PCID.
+ */
+#define INVLPGB_VA BIT(0)
+#define INVLPGB_PCID BIT(1)
+#define INVLPGB_ASID BIT(2)
+#define INVLPGB_INCLUDE_GLOBAL BIT(3)
+#define INVLPGB_FINAL_ONLY BIT(4)
+#define INVLPGB_INCLUDE_NESTED BIT(5)
+
+/* Flush all mappings for a given pcid and addr, not including globals. */
+static inline void invlpgb_flush_user(unsigned long pcid,
+ unsigned long addr)
+{
+ __invlpgb(0, pcid, addr, 0, 0, INVLPGB_PCID | INVLPGB_VA);
+ tlbsync();
+}
+
+static inline void invlpgb_flush_user_nr_nosync(unsigned long pcid,
+ unsigned long addr,
+ u16 nr,
+ bool pmd_stride)
+{
+ __invlpgb(0, pcid, addr, nr - 1, pmd_stride, INVLPGB_PCID | INVLPGB_VA);
+}
+
+/* Flush all mappings for a given PCID, not including globals. */
+static inline void invlpgb_flush_single_pcid_nosync(unsigned long pcid)
+{
+ __invlpgb(0, pcid, 0, 0, 0, INVLPGB_PCID);
+}
+
+/* Flush all mappings, including globals, for all PCIDs. */
+static inline void invlpgb_flush_all(void)
+{
+ __invlpgb(0, 0, 0, 0, 0, INVLPGB_INCLUDE_GLOBAL);
+ tlbsync();
+}
+
+/* Flush addr, including globals, for all PCIDs. */
+static inline void invlpgb_flush_addr_nosync(unsigned long addr, u16 nr)
+{
+ __invlpgb(0, 0, addr, nr - 1, 0, INVLPGB_INCLUDE_GLOBAL);
+}
+
+/* Flush all mappings for all PCIDs except globals. */
+static inline void invlpgb_flush_all_nonglobals(void)
+{
+ __invlpgb(0, 0, 0, 0, 0, 0);
+ tlbsync();
+}
+
+#endif /* _ASM_X86_INVLPGB */
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 8fe3b2dda507..dba5caa4a9f4 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -10,6 +10,7 @@
#include <asm/cpufeature.h>
#include <asm/special_insns.h>
#include <asm/smp.h>
+#include <asm/invlpgb.h>
#include <asm/invpcid.h>
#include <asm/pti.h>
#include <asm/processor-flags.h>
--
2.47.1