[PATCH v13 03/14] x86/mm: add INVLPGB support code

Rik van Riel
2025-02-23T19:50:15Z

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

All the functions defined in invlpgb.h are used later in the series.

Compile time disabling X86_FEATURE_INVLPGB when the config
option is not set allows the compiler to omit unnecessary code.

Signed-off-by: Rik van Riel <riel@surriel.com>
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
Tested-by: Brendan Jackman <jackmanb@google.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/include/asm/disabled-features.h | 9 ++-
arch/x86/include/asm/tlb.h | 92 ++++++++++++++++++++++++
2 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index c492bdc97b05..95997caf0935 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -129,6 +129,13 @@
#define DISABLE_SEV_SNP (1 << (X86_FEATURE_SEV_SNP & 31))
#endif

+#ifdef CONFIG_X86_BROADCAST_TLB_FLUSH
+#define DISABLE_INVLPGB 0
+#else
+/* Keep 32 bit kernels smaller by compiling out the INVLPGB code. */
+#define DISABLE_INVLPGB (1 << (X86_FEATURE_INVLPGB & 31))
+#endif
+
/*
* Make sure to add features to the correct mask
*/
@@ -146,7 +153,7 @@
#define DISABLED_MASK11 (DISABLE_RETPOLINE|DISABLE_RETHUNK|DISABLE_UNRET| \
DISABLE_CALL_DEPTH_TRACKING|DISABLE_USER_SHSTK)
#define DISABLED_MASK12 (DISABLE_FRED|DISABLE_LAM)
-#define DISABLED_MASK13 0
+#define DISABLED_MASK13 (DISABLE_INVLPGB)
#define DISABLED_MASK14 0
#define DISABLED_MASK15 0
#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP| \
diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
index 77f52bc1578a..b3cd521e5e2f 100644
--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -6,6 +6,9 @@
static inline void tlb_flush(struct mmu_gather *tlb);

#include <asm-generic/tlb.h>
+#include <linux/kernel.h>
+#include <vdso/bits.h>
+#include <vdso/page.h>

static inline void tlb_flush(struct mmu_gather *tlb)
{
@@ -25,4 +28,93 @@ static inline void invlpg(unsigned long addr)
asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
}

+
+/*
+ * 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.
+ *
+ * The instruction takes the number of extra pages to invalidate, beyond
+ * the first page, while __invlpgb gets the more human readable number of
+ * pages to invalidate.
+ *
+ * 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 nr_pages,
+ bool pmd_stride, u8 flags)
+{
+ u32 edx = (pcid << 16) | asid;
+ u32 ecx = (pmd_stride << 31) | (nr_pages - 1);
+ 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)
+
+static inline void invlpgb_flush_user_nr_nosync(unsigned long pcid,
+ unsigned long addr,
+ u16 nr,
+ bool pmd_stride)
+{
+ __invlpgb(0, pcid, addr, nr, 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, 1, 0, INVLPGB_PCID);
+}
+
+/* Flush all mappings, including globals, for all PCIDs. */
+static inline void invlpgb_flush_all(void)
+{
+ __invlpgb(0, 0, 0, 1, 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, 0, INVLPGB_INCLUDE_GLOBAL);
+}
+
+/* Flush all mappings for all PCIDs except globals. */
+static inline void invlpgb_flush_all_nonglobals(void)
+{
+ __invlpgb(0, 0, 0, 1, 0, 0);
+ __tlbsync();
+}
+
#endif /* _ASM_X86_TLB_H */
--
2.47.1