diff options
| -rw-r--r-- | arch/riscv/kvm/nacl.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/arch/riscv/kvm/nacl.c b/arch/riscv/kvm/nacl.c index 9aff03c4f667..a5cda9a65156 100644 --- a/arch/riscv/kvm/nacl.c +++ b/arch/riscv/kvm/nacl.c @@ -42,12 +42,24 @@ again: } } - entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_CONFIG(i); - *entp = cpu_to_lelong(control); + /* + * Per SBI v3.0 section 15.1.2, the Page_Number and Page_Count + * words must be updated before the Config word with its Pending + * bit set. WRITE_ONCE() stops the compiler from reordering the + * stores and smp_wmb() makes the parameter words globally + * visible to the SBI implementation (or NACL hardware) before + * the Pending bit is set. + */ entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PNUM(i); - *entp = cpu_to_lelong(page_num); + WRITE_ONCE(*entp, cpu_to_lelong(page_num)); entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PCOUNT(i); - *entp = cpu_to_lelong(page_count); + WRITE_ONCE(*entp, cpu_to_lelong(page_count)); + + /* Ensure the parameter words are visible before the Pending bit */ + smp_wmb(); + + entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_CONFIG(i); + WRITE_ONCE(*entp, cpu_to_lelong(control)); } int kvm_riscv_nacl_enable(void) |