[RFC PATCH 09/34] riscv: kvm: remove stack copy address of pXd in pXd_offset()

[Yeoreum Yun]

We want to change how pXdp_get() works with generic compile-time folded
page tables. To prepare for that, rework get_hva_mapping_size() to avoid
use of a stack copy of a pXd and pass it as argument to pXd_offset() so that
the folded entries value is ignored.

Replace direct uses of stack-based pXd values with pXd_offset_lockless()
and there should be no functional change.

Signed-off-by: Yeoreum Yun <yeoreum.yun at arm.com>
---
 arch/riscv/kvm/mmu.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 082f9b2617338..6d6042b81d790 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -362,10 +362,10 @@ static int get_hva_mapping_size(struct kvm *kvm,
 {
 	int size = PAGE_SIZE;
 	unsigned long flags;
-	pgd_t pgd;
-	p4d_t p4d;
-	pud_t pud;
-	pmd_t pmd;
+	pgd_t *pgdp, pgd;
+	p4d_t *p4dp, p4d;
+	pud_t *pudp, pud;
+	pmd_t *pmdp, pmd;
 
 	/*
 	 * Disable IRQs to prevent concurrent tear down of host page tables,
@@ -381,15 +381,18 @@ static int get_hva_mapping_size(struct kvm *kvm,
 	 * value) and then p*d_offset() walks into the target huge page instead
 	 * of the old page table (sees the new value).
 	 */
-	pgd = pgdp_get(pgd_offset(kvm->mm, hva));
+	pgdp = pgd_offset(kvm->mm, hva);
+	pgd = pgdp_get(pgdp);
 	if (pgd_none(pgd))
 		goto out;
 
-	p4d = p4dp_get(p4d_offset(&pgd, hva));
+	p4dp = p4d_offset_lockless(pgdp, pgd, hva);
+	p4d = p4dp_get(p4dp);
 	if (p4d_none(p4d) || !p4d_present(p4d))
 		goto out;
 
-	pud = pudp_get(pud_offset(&p4d, hva));
+	pudp = pud_offset_lockless(p4dp, p4d, hva);
+	pud = pudp_get(pudp);
 	if (pud_none(pud) || !pud_present(pud))
 		goto out;
 
@@ -398,7 +401,8 @@ static int get_hva_mapping_size(struct kvm *kvm,
 		goto out;
 	}
 
-	pmd = pmdp_get(pmd_offset(&pud, hva));
+	pmdp = pmd_offset_lockless(pudp, pud, hva);
+	pmd = pmdp_get(pmdp);
 	if (pmd_none(pmd) || !pmd_present(pmd))
 		goto out;
 
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}