From:   wefu@redhat.com
To:     anup.patel@wdc.com, atishp04@gmail.com, palmer@dabbelt.com,
        guoren@kernel.org, christoph.muellner@vrull.eu,
        philipp.tomsich@vrull.eu, hch@lst.de, liush@allwinnertech.com,
        wefu@redhat.com, lazyparser@gmail.com, drew@beagleboard.org
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        taiten.peng@canonical.com, aniket.ponkshe@canonical.com,
        heinrich.schuchardt@canonical.com, gordan.markus@canonical.com,
        guoren@linux.alibaba.com, arnd@arndb.de, wens@csie.org,
        maxime@cerno.tech, dlustig@nvidia.com, gfavor@ventanamicro.com,
        andrea.mondelli@huawei.com, behrensj@mit.edu, xinhaoqu@huawei.com,
        huffman@cadence.com, mick@ics.forth.gr,
        allen.baum@esperantotech.com, jscheid@ventanamicro.com,
        rtrauben@gmail.com, Palmer Dabbelt <palmerdabbelt@google.com>,
        Atish Patra <atish.patra@wdc.com>
Subject: [PATCH V4 2/2] riscv: add RISC-V Svpbmt extension supports
Date:   Mon, 29 Nov 2021 09:40:07 +0800
Message-Id: <20211129014007.286478-3-wefu@redhat.com>
In-Reply-To: <20211129014007.286478-1-wefu@redhat.com>
References: <20211129014007.286478-1-wefu@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Wei Fu <wefu@redhat.com>

This patch follows the standard pure RISC-V Svpbmt extension in
privilege spec to solve the non-coherent SOC dma synchronization
issues.

Here is the svpbmt PTE format:
| 63 | 62-61 | 60-8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
  N     MT     RSW    D   A   G   U   X   W   R   V
        ^

Of the Reserved bits [63:54] in a leaf PTE, the high bit is already
allocated (as the N bit), so bits [62:61] are used as the MT (aka
MemType) field. This field specifies one of three memory types that
are close equivalents (or equivalent in effect) to the three main x86
and ARMv8 memory types - as shown in the following table.

RISC-V
Encoding &
MemType     RISC-V Description
----------  ------------------------------------------------
00 - PMA    Normal Cacheable, No change to implied PMA memory type
01 - NC     Non-cacheable, idempotent, weakly-ordered Main Memory
10 - IO     Non-cacheable, non-idempotent, strongly-ordered I/O memory
11 - Rsvd   Reserved for future standard use

The standard protection_map[] needn't be modified because the "PMA"
type keeps the highest bits zero. And the whole modification is
limited in the arch/riscv/* and using a global variable
(__svpbmt) as _PAGE_MASK/IO/NOCACHE for pgprot_noncached
(&writecombine) in pgtable.h. We also add _PAGE_CHG_MASK to filter
PFN than before.

Enable it in devicetree - (Add "riscv,svpbmt" in the mmu of cpu node)
 - mmu:
     riscv,svpmbt

Signed-off-by: Wei Fu <wefu@redhat.com>
Co-developed-by: Liu Shaohua <liush@allwinnertech.com>
Signed-off-by: Liu Shaohua <liush@allwinnertech.com>
Co-developed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Anup Patel <anup.patel@wdc.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: Drew Fustini <drew@beagleboard.org>
Cc: Wei Fu <wefu@redhat.com>
Cc: Wei Wu <lazyparser@gmail.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Greg Favor <gfavor@ventanamicro.com>
Cc: Andrea Mondelli <andrea.mondelli@huawei.com>
Cc: Jonathan Behrens <behrensj@mit.edu>
Cc: Xinhaoqu (Freddie) <xinhaoqu@huawei.com>
Cc: Bill Huffman <huffman@cadence.com>
Cc: Nick Kossifidis <mick@ics.forth.gr>
Cc: Allen Baum <allen.baum@esperantotech.com>
Cc: Josh Scheid <jscheid@ventanamicro.com>
Cc: Richard Trauben <rtrauben@gmail.com>
---
 arch/riscv/include/asm/fixmap.h       |  2 +-
 arch/riscv/include/asm/pgtable-64.h   | 21 ++++++++++++---
 arch/riscv/include/asm/pgtable-bits.h | 39 +++++++++++++++++++++++++--
 arch/riscv/include/asm/pgtable.h      | 39 ++++++++++++++++++++-------
 arch/riscv/kernel/cpufeature.c        | 35 ++++++++++++++++++++++++
 arch/riscv/mm/init.c                  |  5 ++++
 6 files changed, 126 insertions(+), 15 deletions(-)

diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 54cbf07fb4e9..5acd99d08e74 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -43,7 +43,7 @@ enum fixed_addresses {
 	__end_of_fixed_addresses
 };
 
-#define FIXMAP_PAGE_IO		PAGE_KERNEL
+#define FIXMAP_PAGE_IO		PAGE_IOREMAP
 
 #define __early_set_fixmap	__set_fixmap
 
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 228261aa9628..16d251282b1d 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -59,14 +59,29 @@ static inline void pud_clear(pud_t *pudp)
 	set_pud(pudp, __pud(0));
 }
 
+static inline unsigned long _chg_of_pmd(pmd_t pmd)
+{
+	return (pmd_val(pmd) & _PAGE_CHG_MASK);
+}
+
+static inline unsigned long _chg_of_pud(pud_t pud)
+{
+	return (pud_val(pud) & _PAGE_CHG_MASK);
+}
+
+static inline unsigned long _chg_of_pte(pte_t pte)
+{
+	return (pte_val(pte) & _PAGE_CHG_MASK);
+}
+
 static inline pmd_t *pud_pgtable(pud_t pud)
 {
-	return (pmd_t *)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT);
+	return (pmd_t *)pfn_to_virt(_chg_of_pud(pud) >> _PAGE_PFN_SHIFT);
 }
 
 static inline struct page *pud_page(pud_t pud)
 {
-	return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT);
+	return pfn_to_page(_chg_of_pud(pud) >> _PAGE_PFN_SHIFT);
 }
 
 static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
@@ -76,7 +91,7 @@ static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
 
 static inline unsigned long _pmd_pfn(pmd_t pmd)
 {
-	return pmd_val(pmd) >> _PAGE_PFN_SHIFT;
+	return _chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT;
 }
 
 #define mk_pmd(page, prot)    pfn_pmd(page_to_pfn(page), prot)
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index 2ee413912926..e5b0fce4ddc5 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -7,7 +7,7 @@
 #define _ASM_RISCV_PGTABLE_BITS_H
 
 /*
- * PTE format:
+ * rv32 PTE format:
  * | XLEN-1  10 | 9             8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
  *       PFN      reserved for SW   D   A   G   U   X   W   R   V
  */
@@ -24,6 +24,40 @@
 #define _PAGE_DIRTY     (1 << 7)    /* Set by hardware on any write */
 #define _PAGE_SOFT      (1 << 8)    /* Reserved for software */
 
+#if !defined(__ASSEMBLY__) && defined(CONFIG_64BIT)
+/*
+ * rv64 PTE format:
+ * | 63 | 62 61 | 60 54 | 53  10 | 9             8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
+ *   N      MT     RSV    PFN      reserved for SW   D   A   G   U   X   W   R   V
+ * [62:61] Memory Type definitions:
+ *  00 - PMA    Normal Cacheable, No change to implied PMA memory type
+ *  01 - NC     Non-cacheable, idempotent, weakly-ordered Main Memory
+ *  10 - IO     Non-cacheable, non-idempotent, strongly-ordered I/O memory
+ *  11 - Rsvd   Reserved for future standard use
+ */
+#define _SVPBMT_PMA		0UL
+#define _SVPBMT_NC		(1UL << 61)
+#define _SVPBMT_IO		(1UL << 62)
+#define _SVPBMT_MASK		(_SVPBMT_NC | _SVPBMT_IO)
+
+extern struct __svpbmt_struct {
+	unsigned long mask;
+	unsigned long pma;
+	unsigned long nocache;
+	unsigned long io;
+} __svpbmt __cacheline_aligned;
+
+#define _PAGE_MASK		__svpbmt.mask
+#define _PAGE_PMA		__svpbmt.pma
+#define _PAGE_NOCACHE		__svpbmt.nocache
+#define _PAGE_IO		__svpbmt.io
+#else
+#define _PAGE_MASK		0
+#define _PAGE_PMA		0
+#define _PAGE_NOCACHE		0
+#define _PAGE_IO		0
+#endif /* !__ASSEMBLY__ && CONFIG_64BIT */
+
 #define _PAGE_SPECIAL   _PAGE_SOFT
 #define _PAGE_TABLE     _PAGE_PRESENT
 
@@ -38,7 +72,8 @@
 /* Set of bits to preserve across pte_modify() */
 #define _PAGE_CHG_MASK  (~(unsigned long)(_PAGE_PRESENT | _PAGE_READ |	\
 					  _PAGE_WRITE | _PAGE_EXEC |	\
-					  _PAGE_USER | _PAGE_GLOBAL))
+					  _PAGE_USER | _PAGE_GLOBAL |	\
+					  _PAGE_MASK))
 /*
  * when all of R/W/X are zero, the PTE is a pointer to the next level
  * of the page table; otherwise, it is a leaf PTE.
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index bf204e7c1f74..0f7a6541015f 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -138,7 +138,8 @@
 				| _PAGE_PRESENT \
 				| _PAGE_ACCESSED \
 				| _PAGE_DIRTY \
-				| _PAGE_GLOBAL)
+				| _PAGE_GLOBAL \
+				| _PAGE_PMA)
 
 #define PAGE_KERNEL		__pgprot(_PAGE_KERNEL)
 #define PAGE_KERNEL_READ	__pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
@@ -148,11 +149,9 @@
 
 #define PAGE_TABLE		__pgprot(_PAGE_TABLE)
 
-/*
- * The RISC-V ISA doesn't yet specify how to query or modify PMAs, so we can't
- * change the properties of memory regions.
- */
-#define _PAGE_IOREMAP _PAGE_KERNEL
+#define _PAGE_IOREMAP	((_PAGE_KERNEL & ~_PAGE_MASK) | _PAGE_IO)
+
+#define PAGE_IOREMAP		__pgprot(_PAGE_IOREMAP)
 
 extern pgd_t swapper_pg_dir[];
 
@@ -232,12 +231,12 @@ static inline unsigned long _pgd_pfn(pgd_t pgd)
 
 static inline struct page *pmd_page(pmd_t pmd)
 {
-	return pfn_to_page(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+	return pfn_to_page(_chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT);
 }
 
 static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 {
-	return (unsigned long)pfn_to_virt(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+	return (unsigned long)pfn_to_virt(_chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT);
 }
 
 static inline pte_t pmd_pte(pmd_t pmd)
@@ -253,7 +252,7 @@ static inline pte_t pud_pte(pud_t pud)
 /* Yields the page frame number (PFN) of a page table entry */
 static inline unsigned long pte_pfn(pte_t pte)
 {
-	return (pte_val(pte) >> _PAGE_PFN_SHIFT);
+	return (_chg_of_pte(pte) >> _PAGE_PFN_SHIFT);
 }
 
 #define pte_page(x)     pfn_to_page(pte_pfn(x))
@@ -492,6 +491,28 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 	return ptep_test_and_clear_young(vma, address, ptep);
 }
 
+#define pgprot_noncached pgprot_noncached
+static inline pgprot_t pgprot_noncached(pgprot_t _prot)
+{
+	unsigned long prot = pgprot_val(_prot);
+
+	prot &= ~_PAGE_MASK;
+	prot |= _PAGE_IO;
+
+	return __pgprot(prot);
+}
+
+#define pgprot_writecombine pgprot_writecombine
+static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
+{
+	unsigned long prot = pgprot_val(_prot);
+
+	prot &= ~_PAGE_MASK;
+	prot |= _PAGE_NOCACHE;
+
+	return __pgprot(prot);
+}
+
 /*
  * THP functions
  */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index d959d207a40d..fa7480cb8b87 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -8,6 +8,7 @@
 
 #include <linux/bitmap.h>
 #include <linux/of.h>
+#include <linux/pgtable.h>
 #include <asm/processor.h>
 #include <asm/hwcap.h>
 #include <asm/smp.h>
@@ -59,6 +60,38 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
 }
 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
 
+static void __init mmu_supports_svpbmt(void)
+{
+#if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
+	struct device_node *node;
+	const char *str;
+
+	for_each_of_cpu_node(node) {
+		if (of_property_read_string(node, "mmu-type", &str))
+			continue;
+
+		if (!strncmp(str + 6, "none", 4))
+			continue;
+
+		if (of_property_read_string(node, "mmu", &str))
+			continue;
+
+		if (strncmp(str + 6, "svpmbt", 6))
+			continue;
+	}
+
+	__svpbmt.pma		= _SVPBMT_PMA;
+	__svpbmt.nocache	= _SVPBMT_NC;
+	__svpbmt.io		= _SVPBMT_IO;
+	__svpbmt.mask		= _SVPBMT_MASK;
+#endif
+}
+
+static void __init mmu_supports(void)
+{
+	mmu_supports_svpbmt();
+}
+
 void __init riscv_fill_hwcap(void)
 {
 	struct device_node *node;
@@ -67,6 +100,8 @@ void __init riscv_fill_hwcap(void)
 	size_t i, j, isa_len;
 	static unsigned long isa2hwcap[256] = {0};
 
+	mmu_supports();
+
 	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
 	isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
 	isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 24b2b8044602..e4e658165ee1 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -854,3 +854,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 	return vmemmap_populate_basepages(start, end, node, NULL);
 }
 #endif
+
+#if defined(CONFIG_64BIT)
+struct __svpbmt_struct __svpbmt __ro_after_init;
+EXPORT_SYMBOL(__svpbmt);
+#endif
-- 
2.25.4