[PATCH 2/3] KVM: x86/mmu: Open code GFN "rounding" in TDP MMU

From: Sean Christopherson
Date: Tue Oct 27 2020 - 17:43:07 EST


Drop round_gfn_for_level() and directly use the recently introdocued
KVM_HPAGE_GFN_MASK() macro. Hiding the masking in a "rounding" function
adds an extra "what does this do?" lookup, whereas the concept and usage
of PFN/GFN masks is common enough that it's easy to read the open coded
version without thinking too hard.

No functional change intended.

Cc: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_iter.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c
index c6e914c96641..4175947dc401 100644
--- a/arch/x86/kvm/mmu/tdp_iter.c
+++ b/arch/x86/kvm/mmu/tdp_iter.c
@@ -15,11 +15,6 @@ static void tdp_iter_refresh_sptep(struct tdp_iter *iter)
iter->old_spte = READ_ONCE(*iter->sptep);
}

-static gfn_t round_gfn_for_level(gfn_t gfn, int level)
-{
- return gfn & KVM_HPAGE_GFN_MASK(level);
-}
-
/*
* Sets a TDP iterator to walk a pre-order traversal of the paging structure
* rooted at root_pt, starting with the walk to translate goal_gfn.
@@ -36,7 +31,7 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level,
iter->level = root_level;
iter->pt_path[iter->level - 1] = root_pt;

- iter->gfn = round_gfn_for_level(iter->goal_gfn, iter->level);
+ iter->gfn = iter->goal_gfn & KVM_HPAGE_GFN_MASK(iter->level);
tdp_iter_refresh_sptep(iter);

iter->valid = true;
@@ -82,7 +77,7 @@ static bool try_step_down(struct tdp_iter *iter)

iter->level--;
iter->pt_path[iter->level - 1] = child_pt;
- iter->gfn = round_gfn_for_level(iter->goal_gfn, iter->level);
+ iter->gfn = iter->goal_gfn & KVM_HPAGE_GFN_MASK(iter->level);
tdp_iter_refresh_sptep(iter);

return true;
@@ -124,7 +119,7 @@ static bool try_step_up(struct tdp_iter *iter)
return false;

iter->level++;
- iter->gfn = round_gfn_for_level(iter->gfn, iter->level);
+ iter->gfn &= KVM_HPAGE_GFN_MASK(iter->level);
tdp_iter_refresh_sptep(iter);

return true;
--
2.28.0