riscv: Sync efi page table's kernel mappings before switching
authorAlexandre Ghiti <alexghiti@rivosinc.com>
Mon, 21 Nov 2022 13:33:03 +0000 (14:33 +0100)
committerPalmer Dabbelt <palmer@rivosinc.com>
Tue, 29 Nov 2022 00:36:34 +0000 (16:36 -0800)
commit3f105a742725a1b78766a55169f1d827732e62b8
treeffd9b41180579bb6e8de602c317499ce05ad8cb0
parent1d6b5ed41f8c5c7012dbebe9bc0e2292a5a232b4
riscv: Sync efi page table's kernel mappings before switching

The EFI page table is initially created as a copy of the kernel page table.
With VMAP_STACK enabled, kernel stacks are allocated in the vmalloc area:
if the stack is allocated in a new PGD (one that was not present at the
moment of the efi page table creation or not synced in a previous vmalloc
fault), the kernel will take a trap when switching to the efi page table
when the vmalloc kernel stack is accessed, resulting in a kernel panic.

Fix that by updating the efi kernel mappings before switching to the efi
page table.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Fixes: b91540d52a08 ("RISC-V: Add EFI runtime services")
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20221121133303.1782246-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
arch/riscv/include/asm/efi.h
arch/riscv/include/asm/pgalloc.h