mainline inclusion
from mainline-Linux 6.10-rc6
commit e3ecf2f
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Make sure that the altmap parameter is properly passed on to
vmemmap_populate_hugepages().

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-2-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 6667309
category: feature
bugzilla: RVCK-Project#219

--------------------------------

The RISC-V port copies the PGD table from init_mm/swapper_pg_dir to
all userland page tables, which means that if the PGD level table is
changed, other page tables has to be updated as well.

Instead of having the PGD changes ripple out to all tables, the
synchronization can be avoided by pre-allocating the PGD entries/pages
at boot, avoiding the synchronization all together.

This is currently done for the bpf/modules, and vmalloc PGD regions.
Extend this scheme for the PGD regions touched by memory hotplugging.

Prepare the RISC-V port for memory hotplug by pre-allocate
vmemmap/direct map/kasan entries at the PGD level. This will roughly
waste ~128 (plus 32 if KASAN is enabled) worth of 4K pages when memory
hotplugging is enabled in the kernel configuration.

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-3-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit fe122b8
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Prepare for memory hotplugging support by changing from __init to
__meminit for the page table functions that are used by the upcoming
architecture specific callbacks.

Changing the __init attribute to __meminit, avoids that the functions
are removed after init. The __meminit attribute makes sure the
functions are kept in the kernel text post init, but only if memory
hotplugging is enabled for the build.

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-4-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 007480f
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Add a parameter to the direct map setup function, so it can be used in
arch_add_memory() later.

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-5-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 6e6c5e2
category: feature
bugzilla: RVCK-Project#219

--------------------------------

The pfn_to_kaddr() function is used by KASAN's memory hotplugging
path. Add the missing function to the RISC-V port, so that it can be
built with MHP and CONFIG_KASAN.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-6-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 	c75a74f
category: feature
bugzilla: RVCK-Project#219

--------------------------------

For an architecture to support memory hotplugging, a couple of
callbacks needs to be implemented:

 arch_add_memory()
  This callback is responsible for adding the physical memory into the
  direct map, and call into the memory hotplugging generic code via
  __add_pages() that adds the corresponding struct page entries, and
  updates the vmemmap mapping.

 arch_remove_memory()
  This is the inverse of the callback above.

 vmemmap_free()
  This function tears down the vmemmap mappings (if
  CONFIG_SPARSEMEM_VMEMMAP is enabled), and also deallocates the
  backing vmemmap pages. Note that for persistent memory, an
  alternative allocator for the backing pages can be used; The
  vmem_altmap. This means that when the backing pages are cleared,
  extra care is needed so that the correct deallocation method is
  used.

 arch_get_mappable_range()
  This functions returns the PA range that the direct map can map.
  Used by the MHP internals for sanity checks.

The page table unmap/teardown functions are heavily based on code from
the x86 tree. The same remove_pgd_mapping() function is used in both
vmemmap_free() and arch_remove_memory(), but in the latter function
the backing pages are not removed.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-7-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 37992b7
category: feature
bugzilla: RVCK-Project#219

--------------------------------

During memory hot remove, the ptdump functionality can end up touching
stale data. Avoid any potential crashes (or worse), by holding the
memory hotplug read-lock while traversing the page table.

This change is analogous to arm64's commit bf2b59f ("arm64/mm:
Hold memory hotplug lock while walking for kernel page table dump").

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-8-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit f8c2a24
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Enable ARCH_ENABLE_MEMORY_HOTPLUG and ARCH_ENABLE_MEMORY_HOTREMOVE for
RISC-V.

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-9-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 0546d70
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Now that RISC-V has memory hotplugging support, virtio-mem can be used
on the platform.

Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-10-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 216e04b
category: feature
bugzilla: RVCK-Project#219

--------------------------------

ZONE_DEVICE pages need DEVMAP PTEs support to function
(ARCH_HAS_PTE_DEVMAP). Claim another RSW (reserved for software) bit
in the PTE for DEVMAP mark, add the corresponding helpers, and enable
ARCH_HAS_PTE_DEVMAP for riscv64.

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-11-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>

mainline inclusion
from mainline-Linux 6.10-rc6
commit 4705c15
category: feature
bugzilla: RVCK-Project#219

--------------------------------

Now that DAX is usable, enable the DAX VMEMMAP optimization as well.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240605114100.315918-12-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Gao Rui <gao.rui@zte.com.cn>