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Subject[PATCH] KVM: x86/mmu: Avoid mixing gpa_t with gfn_t in walk_addr_generic()
Date
translate_gpa() returns a GPA, assigning it to 'real_gfn' seems obviously
wrong. There is no real issue because both 'gpa_t' and 'gfn_t' are u64 and
we don't use the value in 'real_gfn' as a GFN, we do

real_gfn = gpa_to_gfn(real_gfn);

instead. 'If you see a "buffalo" sign on an elephant's cage, do not trust
your eyes', but let's fix it for good.

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/mmu/paging_tmpl.h | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index a6d484ea110b..58234bfaca07 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -360,7 +360,6 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
++walker->level;

do {
- gfn_t real_gfn;
unsigned long host_addr;

pt_access = pte_access;
@@ -375,7 +374,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
walker->table_gfn[walker->level - 1] = table_gfn;
walker->pte_gpa[walker->level - 1] = pte_gpa;

- real_gfn = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn),
+ real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn),
nested_access,
&walker->fault);

@@ -389,12 +388,10 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
* information to fix the exit_qualification or exit_info_1
* fields.
*/
- if (unlikely(real_gfn == UNMAPPED_GVA))
+ if (unlikely(real_gpa == UNMAPPED_GVA))
return 0;

- real_gfn = gpa_to_gfn(real_gfn);
-
- host_addr = kvm_vcpu_gfn_to_hva_prot(vcpu, real_gfn,
+ host_addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gpa_to_gfn(real_gpa),
&walker->pte_writable[walker->level - 1]);
if (unlikely(kvm_is_error_hva(host_addr)))
goto error;
--
2.25.4
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