git: 0e9a3bdeb737 - stable/14 - pmap: Degrade pmap_page_set_attr*() into a no-op on same attribute

The branch stable/14 has been updated by olce:

URL: https://cgit.FreeBSD.org/src/commit/?id=0e9a3bdeb7376bf04cf21830c4e33aa7efe13961

commit 0e9a3bdeb7376bf04cf21830c4e33aa7efe13961
Author:     Olivier Certner <olce@FreeBSD.org>
AuthorDate: 2025-07-08 16:17:30 +0000
Commit:     Olivier Certner <olce@FreeBSD.org>
CommitDate: 2025-07-28 13:28:51 +0000

    pmap: Degrade pmap_page_set_attr*() into a no-op on same attribute
    
    For 32-bit arm, move the no-op test that was already in place at start
    of the function so that it stays first even if the '#if 0' block around
    the call to sf_buf_invalidate_cache() is uncommented at some point (if
    ever).
    
    Reviewed by:    jeffpc_josefsipek.net, kib
    MFC after:      10 days
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D51253
    
    (cherry picked from commit 9d1f3ce79d85855399663e3977766ec46f28cadd)
    
    Forgotten on commit to main/-CURRENT:
    PR:             277476
---
 sys/amd64/amd64/pmap.c      |  5 +++++
 sys/arm/arm/pmap-v6.c       | 32 +++++++++++++++-----------------
 sys/arm64/arm64/pmap.c      |  2 ++
 sys/i386/i386/pmap.c        |  2 ++
 sys/powerpc/aim/mmu_oea.c   |  3 +++
 sys/powerpc/aim/mmu_oea64.c |  3 +++
 sys/powerpc/aim/mmu_radix.c |  4 ++++
 sys/riscv/riscv/pmap.c      |  2 ++
 8 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 34c7c1c94737..b9681da13d3a 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -9620,6 +9620,8 @@ pmap_demote_pdpe(pmap_t pmap, pdp_entry_t *pdpe, vm_offset_t va, vm_page_t m)
 void
 pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 {
+	if (m->md.pat_mode == ma)
+		return;
 
 	m->md.pat_mode = ma;
 
@@ -9639,6 +9641,9 @@ pmap_page_set_memattr_noflush(vm_page_t m, vm_memattr_t ma)
 {
 	int error;
 
+	if (m->md.pat_mode == ma)
+		return;
+
 	m->md.pat_mode = ma;
 
 	if ((m->flags & PG_FICTITIOUS) != 0)
diff --git a/sys/arm/arm/pmap-v6.c b/sys/arm/arm/pmap-v6.c
index 95aeba201e4a..737e215b44b6 100644
--- a/sys/arm/arm/pmap-v6.c
+++ b/sys/arm/arm/pmap-v6.c
@@ -5749,7 +5749,7 @@ pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 
 	CTR5(KTR_PMAP, "%s: page %p - 0x%08X oma: %d, ma: %d", __func__, m,
 	    VM_PAGE_TO_PHYS(m), oma, ma);
-	if ((m->flags & PG_FICTITIOUS) != 0)
+	if (ma == oma || (m->flags & PG_FICTITIOUS) != 0)
 		return;
 #if 0
 	/*
@@ -5766,22 +5766,20 @@ pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 	 * If page is not mapped by sf buffer, map the page
 	 * transient and do invalidation.
 	 */
-	if (ma != oma) {
-		pa = VM_PAGE_TO_PHYS(m);
-		sched_pin();
-		pc = get_pcpu();
-		cmap2_pte2p = pc->pc_cmap2_pte2p;
-		mtx_lock(&pc->pc_cmap_lock);
-		if (pte2_load(cmap2_pte2p) != 0)
-			panic("%s: CMAP2 busy", __func__);
-		pte2_store(cmap2_pte2p, PTE2_KERN_NG(pa, PTE2_AP_KRW,
-		    vm_memattr_to_pte2(ma)));
-		dcache_wbinv_poc((vm_offset_t)pc->pc_cmap2_addr, pa, PAGE_SIZE);
-		pte2_clear(cmap2_pte2p);
-		tlb_flush((vm_offset_t)pc->pc_cmap2_addr);
-		sched_unpin();
-		mtx_unlock(&pc->pc_cmap_lock);
-	}
+	pa = VM_PAGE_TO_PHYS(m);
+	sched_pin();
+	pc = get_pcpu();
+	cmap2_pte2p = pc->pc_cmap2_pte2p;
+	mtx_lock(&pc->pc_cmap_lock);
+	if (pte2_load(cmap2_pte2p) != 0)
+		panic("%s: CMAP2 busy", __func__);
+	pte2_store(cmap2_pte2p, PTE2_KERN_NG(pa, PTE2_AP_KRW,
+	    vm_memattr_to_pte2(ma)));
+	dcache_wbinv_poc((vm_offset_t)pc->pc_cmap2_addr, pa, PAGE_SIZE);
+	pte2_clear(cmap2_pte2p);
+	tlb_flush((vm_offset_t)pc->pc_cmap2_addr);
+	sched_unpin();
+	mtx_unlock(&pc->pc_cmap_lock);
 }
 
 /*
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index ef33a7339b9e..8e3161736467 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -6678,6 +6678,8 @@ pmap_unmapbios(void *p, vm_size_t size)
 void
 pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 {
+	if (m->md.pv_memattr == ma)
+		return;
 
 	m->md.pv_memattr = ma;
 
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index 90ea6e3459cf..d9eeeed69bd5 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -5516,6 +5516,8 @@ __CONCAT(PMTYPE, unmapdev)(void *p, vm_size_t size)
 static void
 __CONCAT(PMTYPE, page_set_memattr)(vm_page_t m, vm_memattr_t ma)
 {
+	if (m->md.pat_mode == ma)
+		return;
 
 	m->md.pat_mode = ma;
 	if ((m->flags & PG_FICTITIOUS) != 0)
diff --git a/sys/powerpc/aim/mmu_oea.c b/sys/powerpc/aim/mmu_oea.c
index 363eb0c4c9a7..662204ec8b33 100644
--- a/sys/powerpc/aim/mmu_oea.c
+++ b/sys/powerpc/aim/mmu_oea.c
@@ -1465,6 +1465,9 @@ moea_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 	pmap_t	pmap;
 	u_int	lo;
 
+	if (m->md.mdpg_cache_attrs == ma)
+		return;
+
 	if ((m->oflags & VPO_UNMANAGED) != 0) {
 		m->md.mdpg_cache_attrs = ma;
 		return;
diff --git a/sys/powerpc/aim/mmu_oea64.c b/sys/powerpc/aim/mmu_oea64.c
index 4266047ee3e2..2ded3b6b5195 100644
--- a/sys/powerpc/aim/mmu_oea64.c
+++ b/sys/powerpc/aim/mmu_oea64.c
@@ -2121,6 +2121,9 @@ moea64_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 	CTR3(KTR_PMAP, "%s: pa=%#jx, ma=%#x",
 	    __func__, (uintmax_t)VM_PAGE_TO_PHYS(m), ma);
 
+	if (m->md.mdpg_cache_attrs == ma)
+		return;
+
 	if ((m->oflags & VPO_UNMANAGED) != 0) {
 		m->md.mdpg_cache_attrs = ma;
 		return;
diff --git a/sys/powerpc/aim/mmu_radix.c b/sys/powerpc/aim/mmu_radix.c
index a15f686d88fe..78c57badee55 100644
--- a/sys/powerpc/aim/mmu_radix.c
+++ b/sys/powerpc/aim/mmu_radix.c
@@ -5888,6 +5888,10 @@ mmu_radix_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 {
 
 	CTR3(KTR_PMAP, "%s(%p, %#x)", __func__, m, ma);
+
+	if (m->md.mdpg_cache_attrs == ma)
+		return;
+
 	m->md.mdpg_cache_attrs = ma;
 
 	/*
diff --git a/sys/riscv/riscv/pmap.c b/sys/riscv/riscv/pmap.c
index 4812f3274e69..74bbddd7b065 100644
--- a/sys/riscv/riscv/pmap.c
+++ b/sys/riscv/riscv/pmap.c
@@ -4589,6 +4589,8 @@ pmap_unmapbios(void *p, vm_size_t size)
 void
 pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 {
+	if (m->md.pv_memattr == ma)
+		return;
 
 	m->md.pv_memattr = ma;