linux-kernel - [PATCH v5 05/12] x86/mm: add INVLPGB support code

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Message-ID: <20250116023127.1531583-6-riel@surriel.com>
Date: Wed, 15 Jan 2025 21:30:28 -0500
From: Rik van Riel <riel@...riel.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	bp@...en8.de,
	peterz@...radead.org,
	dave.hansen@...ux.intel.com,
	zhengqi.arch@...edance.com,
	nadav.amit@...il.com,
	thomas.lendacky@....com,
	kernel-team@...a.com,
	linux-mm@...ck.org,
	akpm@...ux-foundation.org,
	jannh@...gle.com,
	mhklinux@...look.com,
	andrew.cooper3@...rix.com,
	Rik van Riel <riel@...riel.com>
Subject: [PATCH v5 05/12] x86/mm: add INVLPGB support code

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@...riel.com>
---
 arch/x86/include/asm/invlpgb.h  | 97 +++++++++++++++++++++++++++++++++
 arch/x86/include/asm/tlbflush.h |  1 +
 2 files changed, 98 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..4dfd09e65fa6
--- /dev/null
+++ b/arch/x86/include/asm/invlpgb.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_INVLPGB
+#define _ASM_X86_INVLPGB
+
+#include <linux/kernel.h>
+#include <vdso/bits.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, unsigned long flags)
+{
+	u32 edx = (pcid << 16) | asid;
+	u32 ecx = (pmd_stride << 31) | extra_count;
+	u64 rax = addr | flags;
+
+	/* 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