Re: [PATCH v3 27/32] KVM: arm64: Refactor stage2_map_set_prot_attr()

On Thursday 04 Mar 2021 at 20:03:36 (+0000), Will Deacon wrote:

On Tue, Mar 02, 2021 at 02:59:57PM +0000, Quentin Perret wrote:

quoted

In order to ease its re-use in other code paths, refactor
stage2_map_set_prot_attr() to not depend on a stage2_map_data struct.
No functional change intended.

Signed-off-by: Quentin Perret <redacted>
---
 arch/arm64/kvm/hyp/pgtable.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 8e7059fcfd40..8aa01a9e2603 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c

@@ -494,8 +494,7 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
 	return vtcr;
 }
 
-static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
-				    struct stage2_map_data *data)
+static kvm_pte_t stage2_get_prot_attr(enum kvm_pgtable_prot prot)
 {
 	bool device = prot & KVM_PGTABLE_PROT_DEVICE;
 	kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :

@@ -504,15 +503,15 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
 
 	if (prot & KVM_PGTABLE_PROT_NONE) {
 		if (prot != KVM_PGTABLE_PROT_NONE)
-			return -EINVAL;
+			return 0;

Hmm, does the architecture actually say that having all these attributes
as 0 is illegal?

Hmm, that's a good point, that might not be the case. I assumed we would
have no use for this, but there we can easily avoid the restriction
so...

If not, I think it would be better to keep the int return
code and replace the 'data' parameter with a pointer to a kvm_pte_t.

Does that work?

I think so yes, I'll fix it up.

Cheers,
Quentin

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