git: 99360212c739 - main - riscv/pmap.c: Add an Svinval-aware variant of pmap_invalidate_range

The branch main has been updated by bnovkov:

URL: https://cgit.FreeBSD.org/src/commit/?id=99360212c7392f2b0b3932b40f005c71e943b65f

commit 99360212c7392f2b0b3932b40f005c71e943b65f
Author:     Bojan Novković <bnovkov@FreeBSD.org>
AuthorDate: 2026-06-16 14:55:48 +0000
Commit:     Bojan Novković <bnovkov@FreeBSD.org>
CommitDate: 2026-08-10 16:01:28 +0000

    riscv/pmap.c: Add an Svinval-aware variant of pmap_invalidate_range
    
    This change introduces a variant of `pmap_invalidate_range` that uses
    the fine-grained TLB invalidation instructions introduced by the
    Svinval extension. These instructions allow for more efficient TLB
    flushing on certain implementations. Under this new scheme,
    `pmap_invalidate_range` was converted to an ifunc that selects the
    appropriate variant during boot.
    
    Event:  BSDCan 2026
    Reviewed by:    markj, mhorne
    Differential Revision:  https://reviews.freebsd.org/D57624
---
 sys/riscv/riscv/pmap.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/sys/riscv/riscv/pmap.c b/sys/riscv/riscv/pmap.c
index 67123f9bfcc8..b3f03eeaab9f 100644
--- a/sys/riscv/riscv/pmap.c
+++ b/sys/riscv/riscv/pmap.c
@@ -159,6 +159,7 @@
 
 #include <machine/machdep.h>
 #include <machine/md_var.h>
+#include <machine/ifunc.h>
 #include <machine/pcb.h>
 #include <machine/sbi.h>
 #include <machine/thead.h>
@@ -345,6 +346,7 @@ static int pmap_unuse_pt(pmap_t, vm_offset_t, pd_entry_t, struct spglist *);
 static int pmap_change_attr_locked(void *va, vm_size_t size, int mode);
 
 static uint64_t pmap_satp_mode(void);
+static void pmap_invalidate_all(pmap_t pmap);
 
 #define	pmap_clear(pte)			pmap_store(pte, 0)
 #define	pmap_clear_bits(pte, bits)	atomic_clear_64(pte, bits)
@@ -1077,7 +1079,7 @@ pmap_init(void)
  * sfence_vma() on remote CPUs.
  */
 static void
-pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
+pmap_invalidate_page_sbi(pmap_t pmap, vm_offset_t va)
 {
 	cpuset_t mask;
 
@@ -1092,7 +1094,7 @@ pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
 }
 
 static void
-pmap_invalidate_range(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
+pmap_invalidate_range_sbi(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
 {
 	cpuset_t mask;
 
@@ -1111,6 +1113,73 @@ pmap_invalidate_range(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
 	sched_unpin();
 }
 
+#define PMAP_SVINVAL_THRESHOLD (2 * L2_SIZE)
+
+struct svinval_args {
+	vm_offset_t sva;
+	vm_offset_t eva;
+};
+
+static void
+pmap_invalidate_range_svinval_cb(void *arg)
+{
+	struct svinval_args *args = arg;
+	vm_offset_t va;
+
+	sfence_w_inval();
+	for (va = args->sva; va < args->eva; va += PAGE_SIZE)
+		sinval_vma_page(va);
+	sfence_inval_ir();
+}
+
+static void
+pmap_invalidate_range_svinval(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
+{
+	struct svinval_args args;
+
+	if (CPU_EMPTY(&pmap->pm_active))
+		return;
+
+	if (eva - sva >= PMAP_SVINVAL_THRESHOLD) {
+		pmap_invalidate_all(pmap);
+		return;
+	}
+
+	sched_pin();
+	args.sva = sva;
+	args.eva = eva;
+	fence();
+	if (smp_started)
+		smp_rendezvous_cpus(pmap->pm_active, smp_no_rendezvous_barrier,
+		    pmap_invalidate_range_svinval_cb,
+		    smp_no_rendezvous_barrier, &args);
+	else
+		pmap_invalidate_range_svinval_cb(&args);
+	sched_unpin();
+}
+
+static void
+pmap_invalidate_page_svinval(pmap_t pmap, vm_offset_t va)
+{
+	pmap_invalidate_range_svinval(pmap, va, va + PAGE_SIZE);
+}
+
+DEFINE_IFUNC(, void, pmap_invalidate_range,
+    (pmap_t pmap, vm_offset_t sva, vm_offset_t eva))
+{
+	if (has_svinval)
+		return (pmap_invalidate_range_svinval);
+	return (pmap_invalidate_range_sbi);
+}
+
+DEFINE_IFUNC(, void, pmap_invalidate_page,
+    (pmap_t pmap, vm_offset_t va))
+{
+	if (has_svinval)
+		return (pmap_invalidate_page_svinval);
+	return (pmap_invalidate_page_sbi);
+}
+
 static void
 pmap_invalidate_all(pmap_t pmap)
 {