Revert "riscv: mm: support Svnapot in huge vmap"

This reverts commit ce173474cf19fe7fbe8f0fc74e3c81ec9c3d9807.

We cannot correctly deal with NAPOT mappings in vmalloc/vmap because if
some part of a NAPOT mapping is unmapped, the remaining mapping is not
updated accordingly. For example:

ptr = vmalloc_huge(64 * 1024, GFP_KERNEL);
vunmap_range((unsigned long)(ptr + PAGE_SIZE),
(unsigned long)(ptr + 64 * 1024));

leads to the following kernel page table dump:

0xffff8f8000ef0000-0xffff8f8000ef1000 0x00000001033c0000 4K PTE N .. .. D A G . . W R V

Meaning the first entry which was not unmapped still has the N bit set,
which, if accessed first and cached in the TLB, could allow access to the
unmapped range.

That's because the logic to break the NAPOT mapping does not exist and
likely won't. Indeed, to break a NAPOT mapping, we first have to clear
the whole mapping, flush the TLB and then set the new mapping ("break-
before-make" equivalent). That works fine in userspace since we can handle
any pagefault occurring on the remaining mapping but we can't handle a kernel
pagefault on such mapping.

So fix this by reverting the commit that introduced the vmap/vmalloc
support.

Fixes: ce173474cf19 ("riscv: mm: support Svnapot in huge vmap")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240227205016.121901-2-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: Do not allow vmap pud mappings for 3-level page table

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>
Link: https://lore.kernel.org/r/20230808130709.1502614-1-alexghiti@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: mm: support Svnapot in huge vmap

As HAVE_ARCH_HUGE_VMAP and HAVE_ARCH_HUGE_VMALLOC is supported, we can
implement arch_vmap_pte_range_map_size and arch_vmap_pte_supported_shift
for Svnapot to support huge vmap about napot size.

It can be tested by huge vmap used in pci driver. Huge vmalloc with svnapot
can be tested by test_vmalloc with [1] applied, and probe this
module to run fix_size_alloc_test with use_huge true.

[1]https://lore.kernel.org/all/20221212055657.698420-1-panqinglin2020@iscas.ac.cn/

Signed-off-by: Qinglin Pan <panqinglin00@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230209131647.17245-4-panqinglin00@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: Enable HAVE_ARCH_HUGE_VMAP for 64BIT

This sets the HAVE_ARCH_HUGE_VMAP option, and defines the required page
table functions. With this feature, ioremap area will be mapped with
huge page granularity according to its actual size. This feature can be
disabled by kernel parameter "nohugeiomap".

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Tested-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20221012120038.1034354-2-liushixin2@huawei.com
[Palmer: minor formatting]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

mm/vmalloc: Add empty <asm/vmalloc.h> headers and use them from <linux/vmalloc.h>

In the x86 MM code we'd like to untangle various types of historic
header dependency spaghetti, but for this we'd need to pass to
the generic vmalloc code various vmalloc related defines that
customarily come via the <asm/page.h> low level arch header.

Signed-off-by: Ingo Molnar <mingo@kernel.org>