linux-kernel - [PATCH] KVM: arm64: Fix build error in user_mem

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Date:   Tue,  3 Nov 2020 11:30:09 +1100
From:   Gavin Shan <gshan@...hat.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-kernel@...r.kernel.org, will@...nel.org,
        eric.auger@...hat.com, maz@...nel.org, shan.gavin@...il.com
Subject: [PATCH] KVM: arm64: Fix build error in user_mem_abort()

The PUD and PMD are folded into PGD when the following options are
enabled. In that case, PUD_SHIFT is equal to PMD_SHIFT and we fail
to build with the indicated errors:

   CONFIG_ARM64_VA_BITS_42=y
   CONFIG_ARM64_PAGE_SHIFT=16
   CONFIG_PGTABLE_LEVELS=3

   arch/arm64/kvm/mmu.c: In function ‘user_mem_abort’:
   arch/arm64/kvm/mmu.c:798:2: error: duplicate case value
     case PMD_SHIFT:
     ^~~~
   arch/arm64/kvm/mmu.c:791:2: note: previously used here
     case PUD_SHIFT:
     ^~~~

This fixes the issue by skipping the check on PUD huge page when PUD
and PMD are folded into PGD.

Fixes: 2f40c46021bbb ("KVM: arm64: Use fallback mapping sizes for contiguous huge page sizes")
Reported-by: Eric Auger <eric.auger@...hat.com>
Signed-off-by: Gavin Shan <gshan@...hat.com>
---
 arch/arm64/kvm/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 57972bdb213a..1a01da9fdc99 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -788,10 +788,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	switch (vma_shift) {
+#ifndef __PAGETABLE_PMD_FOLDED
 	case PUD_SHIFT:
 		if (fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
 			break;
 		fallthrough;
+#endif
 	case CONT_PMD_SHIFT:
 		vma_shift = PMD_SHIFT;
 		fallthrough;
-- 
2.23.0