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KVM: arm64: nv: Return correct RES0 bits for FGT registers

PATCH Applied Zenghui Yu 2 participants 3 messages Jan 21 – Jan 22

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Zenghui Yu

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PATCH 1/1 KVM: arm64: nv: Return correct RES0 bits for FGT registers

From: "Zenghui Yu (Huawei)" <[email protected]>

We had extended the sysreg masking infrastructure to more general registers, instead of restricting it to VNCR-backed registers, since commit a0162020095e ("KVM: arm64: Extend masking facility to arbitrary registers"). Fix kvm_get_sysreg_res0() to reflect this fact.

Note that we're sure that we only deal with FGT registers in kvm_get_sysreg_res0(), the

	if (sr < __VNCR_START__)

is actually a never false, which should probably be removed later.

Fixes 69c19e047dfe ("KVM: arm64: Add TCR2_EL2 to the sysreg arrays")
Signed-off-by Zenghui Yu (Huawei) <[email protected]>
---
 arch/arm64/kvm/emulate-nested.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm64/kvm/emulate-nested.c +1 -1
index 834f13fb1fb7..2d04fb56746e 100644
@@ -2428,7 +2428,7 @@ static u64 kvm_get_sysreg_res0(struct kvm *kvm, enum vcpu_sysreg sr)
 
 	masks = kvm->arch.sysreg_masks;
 
-	return masks->mask[sr - __VNCR_START__].res0;
+	return masks->mask[sr - __SANITISED_REG_START__].res0;
 }
 
 static bool check_fgt_bit(struct kvm_vcpu *vcpu, enum vcpu_sysreg sr,
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2.34.1
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#1 lore raw
Quoted 7 lines · Zenghui Yu

From: "Zenghui Yu (Huawei)" <[email protected]>

We had extended the sysreg masking infrastructure to more general registers, instead of restricting it to VNCR-backed registers, since commit a0162020095e ("KVM: arm64: Extend masking facility to arbitrary registers"). Fix kvm_get_sysreg_res0() to reflect this fact.

Huh, what a howler! Thanks a lot for spotting this!

Quoted 7 lines

Note that we're sure that we only deal with FGT registers in kvm_get_sysreg_res0(), the

	if (sr < __VNCR_START__)

is actually a never false, which should probably be removed later.

I think the biggest mistake is to have several places where we perform sysreg index to array index conversions. We should try to unify that.

Quoted 3 lines
Fixes 69c19e047dfe ("KVM: arm64: Add TCR2_EL2 to the sysreg arrays")
Signed-off-by Zenghui Yu (Huawei) <[email protected]>
Cc [email protected]

Thanks again,

	M.
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Without deviation from the norm, progress is not possible.
maintainer Applied
#2 lore raw
In reply to Zenghui Yu
Quoted 9 lines · Zenghui Yu

We had extended the sysreg masking infrastructure to more general registers, instead of restricting it to VNCR-backed registers, since commit a0162020095e ("KVM: arm64: Extend masking facility to arbitrary registers"). Fix kvm_get_sysreg_res0() to reflect this fact.

Note that we're sure that we only deal with FGT registers in kvm_get_sysreg_res0(), the

[...]

Applied to next, thanks!

[1/1] KVM: arm64: nv: Return correct RES0 bits for FGT registers

      commit: 2eb80a2eee18762a33aa770d742d64fe47852c7e

Cheers,

	M.
Signature · 1 line
Without deviation from the norm, progress is not possible.