Rework the function comment for kvm_arch_mmu_enable_log_dirty_pt_masked(), as it has gotten a bit stale, and is the last source of warnings for W=1 builds in KVM x86 due to using a kernel-doc comment without documenting all parameters. Opportunistically subsume the functions comments for kvm_mmu_write_protect_pt_masked() and kvm_mmu_clear_dirty_pt_masked(), as there is no value in regurgitating the same parameter information, and capturing the differences between write-protection and PML-based dirty logging is best done in a common location. No functional change intended. Cc: David Matlack <dmatlack@xxxxxxxxxx> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- I don't actually care too much about the comment itself, I really just want to get rid of the annoying warnings (I was *very* tempted to just delete the extra asterisk), so if anyone has any opinion whatsoever... arch/x86/kvm/mmu/mmu.c | 43 ++++++++++++++++++------------------------ 1 file changed, 18 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index f2c9580d9588..7eb87d473223 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1307,15 +1307,6 @@ static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, return flush; } -/** - * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages - * @kvm: kvm instance - * @slot: slot to protect - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should protect - * - * Used when we do not need to care about huge page mappings. - */ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) @@ -1339,16 +1330,6 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, } } -/** - * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write - * protect the page if the D-bit isn't supported. - * @kvm: kvm instance - * @slot: slot to clear D-bit - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should clear D-bit - * - * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. - */ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) @@ -1373,14 +1354,26 @@ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, } /** - * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected - * PT level pages. + * kvm_arch_mmu_enable_log_dirty_pt_masked - (Re)Enable dirty logging for a set + * of GFNs * - * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to - * enable dirty logging for them. + * @kvm: kvm instance + * @slot: slot to containing the gfns to dirty log + * @gfn_offset: start of the BITS_PER_LONG pages we care about + * @mask: indicates which gfns to dirty log (1 == enable) * - * We need to care about huge page mappings: e.g. during dirty logging we may - * have such mappings. + * (Re)Enable dirty logging for the set of GFNs indicated by the slot, + * gfn_offset, and mask, e.g. after userspace has harvested dirty information + * and wants to re-log dirty GFNs for the next round of migration. + * + * If the slot was assumed to be "initially all dirty", write-protect hugepages + * to ensure they are split to 4KiB on the first write (KVM dirty logs at 4KiB + * granularity). If eager page splitting is enabled, immediately try to split + * hugepages, e.g. so that vCPUs don't get saddled with the cost of the split. + * + * If Page-Modification Logging (PML) is enabled and the GFN doesn't need to be + * write-protected for other reasons, e.g. shadow paging, clear the Dirty Bit. + * Otherwise write-protect the GFN, i.e. clear the Writable Bit. */ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, base-commit: f99b052256f16224687e5947772f0942bff73fc1 -- 2.45.2.505.gda0bf45e8d-goog
