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From: Alexandre Ghiti <alexghiti@rivosinc.com>
To: "Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alexghiti@rivosinc.com>,
	"Björn Töpel" <bjorn@rivosinc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH -fixes] riscv: Do not allow vmap pud mappings for 3-level page table
Date: Tue,  8 Aug 2023 15:07:09 +0200	[thread overview]
Message-ID: <20230808130709.1502614-1-alexghiti@rivosinc.com> (raw)

The vmalloc_fault() path was removed and to avoid syncing the vmalloc PGD
mappings, they are now preallocated. But if the kernel can use a PUD
mapping (which in sv39 is actually a PGD mapping) for large vmalloc
allocation, it will free the current unused preallocated PGD mapping and
install a new leaf one. Since there is no sync anymore, some page tables
lack this new mapping and that triggers a panic.

So only allow PUD mappings for sv48 and sv57.

Fixes: 7d3332be011e ("riscv: mm: Pre-allocate PGD entries for vmalloc/modules area")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/include/asm/vmalloc.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/vmalloc.h b/arch/riscv/include/asm/vmalloc.h
index 58d3e447f191..924d01b56c9a 100644
--- a/arch/riscv/include/asm/vmalloc.h
+++ b/arch/riscv/include/asm/vmalloc.h
@@ -3,12 +3,14 @@
 
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 
+extern bool pgtable_l4_enabled, pgtable_l5_enabled;
+
 #define IOREMAP_MAX_ORDER (PUD_SHIFT)
 
 #define arch_vmap_pud_supported arch_vmap_pud_supported
 static inline bool arch_vmap_pud_supported(pgprot_t prot)
 {
-	return true;
+	return pgtable_l4_enabled || pgtable_l5_enabled;
 }
 
 #define arch_vmap_pmd_supported arch_vmap_pmd_supported
-- 
2.39.2


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WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Ghiti <alexghiti@rivosinc.com>
To: "Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alexghiti@rivosinc.com>,
	"Björn Töpel" <bjorn@rivosinc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH -fixes] riscv: Do not allow vmap pud mappings for 3-level page table
Date: Tue,  8 Aug 2023 15:07:09 +0200	[thread overview]
Message-ID: <20230808130709.1502614-1-alexghiti@rivosinc.com> (raw)

The vmalloc_fault() path was removed and to avoid syncing the vmalloc PGD
mappings, they are now preallocated. But if the kernel can use a PUD
mapping (which in sv39 is actually a PGD mapping) for large vmalloc
allocation, it will free the current unused preallocated PGD mapping and
install a new leaf one. Since there is no sync anymore, some page tables
lack this new mapping and that triggers a panic.

So only allow PUD mappings for sv48 and sv57.

Fixes: 7d3332be011e ("riscv: mm: Pre-allocate PGD entries for vmalloc/modules area")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/include/asm/vmalloc.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/vmalloc.h b/arch/riscv/include/asm/vmalloc.h
index 58d3e447f191..924d01b56c9a 100644
--- a/arch/riscv/include/asm/vmalloc.h
+++ b/arch/riscv/include/asm/vmalloc.h
@@ -3,12 +3,14 @@
 
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 
+extern bool pgtable_l4_enabled, pgtable_l5_enabled;
+
 #define IOREMAP_MAX_ORDER (PUD_SHIFT)
 
 #define arch_vmap_pud_supported arch_vmap_pud_supported
 static inline bool arch_vmap_pud_supported(pgprot_t prot)
 {
-	return true;
+	return pgtable_l4_enabled || pgtable_l5_enabled;
 }
 
 #define arch_vmap_pmd_supported arch_vmap_pmd_supported
-- 
2.39.2


             reply	other threads:[~2023-08-08 13:07 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-08 13:07 Alexandre Ghiti [this message]
2023-08-08 13:07 ` [PATCH -fixes] riscv: Do not allow vmap pud mappings for 3-level page table Alexandre Ghiti
2023-08-10 19:50 ` patchwork-bot+linux-riscv
2023-08-10 19:50   ` patchwork-bot+linux-riscv

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