* [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read()
@ 2018-02-26 22:42 Matthias Kaehlcke
2018-02-26 22:46 ` Guenter Roeck
2018-03-07 18:23 ` Radim Krčmář
0 siblings, 2 replies; 3+ messages in thread
From: Matthias Kaehlcke @ 2018-02-26 22:42 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, H . Peter Anvin
Cc: x86, kvm, linux-kernel, Guenter Roeck, Matthias Kaehlcke
The type 'enum kvm_reg_ex' is an extension of 'enum kvm_reg', however
the extension is only semantical and the compiler doesn't know about the
relationship between the two types. In kvm_pdptr_read() a value of the
extended type is passed to kvm_x86_ops->cache_reg(), which expects a
value of the base type. Clang raises the following warning about the
type mismatch:
arch/x86/kvm/kvm_cache_regs.h:44:32: warning: implicit conversion from
enumeration type 'enum kvm_reg_ex' to different enumeration type
'enum kvm_reg' [-Wenum-conversion]
kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
Cast VCPU_EXREG_PDPTR to 'enum kvm_reg' to make the compiler happy.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
arch/x86/kvm/kvm_cache_regs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index f500293dad8d..58ba12071014 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -41,7 +41,7 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
if (!test_bit(VCPU_EXREG_PDPTR,
(unsigned long *)&vcpu->arch.regs_avail))
- kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
+ kvm_x86_ops->cache_reg(vcpu, (enum kvm_reg)VCPU_EXREG_PDPTR);
return vcpu->arch.walk_mmu->pdptrs[index];
}
--
2.16.1.291.g4437f3f132-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read()
2018-02-26 22:42 [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read() Matthias Kaehlcke
@ 2018-02-26 22:46 ` Guenter Roeck
2018-03-07 18:23 ` Radim Krčmář
1 sibling, 0 replies; 3+ messages in thread
From: Guenter Roeck @ 2018-02-26 22:46 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Paolo Bonzini, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, H . Peter Anvin, x86, kvm,
linux-kernel, Guenter Roeck
On Mon, Feb 26, 2018 at 2:42 PM, Matthias Kaehlcke <mka@chromium.org> wrote:
> The type 'enum kvm_reg_ex' is an extension of 'enum kvm_reg', however
> the extension is only semantical and the compiler doesn't know about the
> relationship between the two types. In kvm_pdptr_read() a value of the
> extended type is passed to kvm_x86_ops->cache_reg(), which expects a
> value of the base type. Clang raises the following warning about the
> type mismatch:
>
> arch/x86/kvm/kvm_cache_regs.h:44:32: warning: implicit conversion from
> enumeration type 'enum kvm_reg_ex' to different enumeration type
> 'enum kvm_reg' [-Wenum-conversion]
> kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
>
> Cast VCPU_EXREG_PDPTR to 'enum kvm_reg' to make the compiler happy.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
> ---
> arch/x86/kvm/kvm_cache_regs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
> index f500293dad8d..58ba12071014 100644
> --- a/arch/x86/kvm/kvm_cache_regs.h
> +++ b/arch/x86/kvm/kvm_cache_regs.h
> @@ -41,7 +41,7 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
>
> if (!test_bit(VCPU_EXREG_PDPTR,
> (unsigned long *)&vcpu->arch.regs_avail))
> - kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
> + kvm_x86_ops->cache_reg(vcpu, (enum kvm_reg)VCPU_EXREG_PDPTR);
>
> return vcpu->arch.walk_mmu->pdptrs[index];
> }
> --
> 2.16.1.291.g4437f3f132-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read()
2018-02-26 22:42 [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read() Matthias Kaehlcke
2018-02-26 22:46 ` Guenter Roeck
@ 2018-03-07 18:23 ` Radim Krčmář
1 sibling, 0 replies; 3+ messages in thread
From: Radim Krčmář @ 2018-03-07 18:23 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Paolo Bonzini, Thomas Gleixner, Ingo Molnar, H . Peter Anvin,
x86, kvm, linux-kernel, Guenter Roeck
2018-02-26 14:42-0800, Matthias Kaehlcke:
> The type 'enum kvm_reg_ex' is an extension of 'enum kvm_reg', however
> the extension is only semantical and the compiler doesn't know about the
> relationship between the two types. In kvm_pdptr_read() a value of the
> extended type is passed to kvm_x86_ops->cache_reg(), which expects a
> value of the base type. Clang raises the following warning about the
> type mismatch:
Yeah, expressing this in C type system seems impossible.
> arch/x86/kvm/kvm_cache_regs.h:44:32: warning: implicit conversion from
> enumeration type 'enum kvm_reg_ex' to different enumeration type
> 'enum kvm_reg' [-Wenum-conversion]
> kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
>
> Cast VCPU_EXREG_PDPTR to 'enum kvm_reg' to make the compiler happy.
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-02-26 22:42 [PATCH] KVM: x86: Make enum conversion explicit in kvm_pdptr_read() Matthias Kaehlcke
2018-02-26 22:46 ` Guenter Roeck
2018-03-07 18:23 ` Radim Krčmář
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