[PATCH V3] KVM: arm64: Implement vq_present() as a macro

[PATCH V3] KVM: arm64: Implement vq_present() as a macro

[Viresh Kumar]

This routine is a one-liner and doesn't really need to be function and
can be implemented as a macro.

Suggested-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
V2->V3:
- Pass "vqs" instead of "&vqs" to vq_present().
- Added Reviewed-by from Dave.

V1->V2:
- The previous implementation was fixing a compilation error that
  occurred only with old compilers (from 2015) due to a bug in the
  compiler itself.

- Dave suggested to rather implement this as a macro which made more
  sense.

 arch/arm64/kvm/guest.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 3ae2f82fca46..ae734fcfd4ea 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -207,13 +207,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64)
 #define vq_mask(vq) ((u64)1 << ((vq) - SVE_VQ_MIN) % 64)
-
-static bool vq_present(
-	const u64 (*const vqs)[KVM_ARM64_SVE_VLS_WORDS],
-	unsigned int vq)
-{
-	return (*vqs)[vq_word(vq)] & vq_mask(vq);
-}
+#define vq_present(vqs, vq) ((vqs)[vq_word(vq)] & vq_mask(vq))
 
 static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {
@@ -258,7 +252,7 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 	max_vq = 0;
 	for (vq = SVE_VQ_MIN; vq <= SVE_VQ_MAX; ++vq)
-		if (vq_present(&vqs, vq))
+		if (vq_present(vqs, vq))
 			max_vq = vq;
 
 	if (max_vq > sve_vq_from_vl(kvm_sve_max_vl))
@@ -272,7 +266,7 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	 * maximum:
 	 */
 	for (vq = SVE_VQ_MIN; vq <= max_vq; ++vq)
-		if (vq_present(&vqs, vq) != sve_vq_available(vq))
+		if (vq_present(vqs, vq) != sve_vq_available(vq))
 			return -EINVAL;
 
 	/* Can't run with no vector lengths at all: */
-- 
2.21.0.rc0.269.g1a574e7a288b

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RE: [PATCH V3] KVM: arm64: Implement vq_present() as a macro

[Zhang, Lei]

Hi guys,

I can't start up KVM guest os with SVE feature with your patch.
The error message is 
qemu-system-aarch64: kvm_init_vcpu failed: Invalid argument.

My test enviroment.
kernel  linux-5.2-rc6
qemu  [Qemu-devel] [PATCH v2 00/14] target/arm/kvm: enable SVE in guests https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04945.html
KVM start up option
-machine virt,gic-version=host,accel=kvm \
-cpu host \
-machine type=virt \
-nographic \
-smp 16 \ -m 4096 \
-drive if=none,file=/root/image.qcow2,id=hd0,format=qcow2 \
-device virtio-blk-device,drive=hd0 \
-netdev user,id=mynet0,restrict=off,hostfwd=tcp::38001-:22 \
-device virtio-net-device,netdev=mynet0 \
-bios /root/QEMU_EFI.fd

sve_vq_available function's return value' type is bool.
But vq_present is macro, so the value is not only TRUE, FALSE but also some numbers.
So It failed at 
if (vq_present(vqs, vq) != sve_vq_available(vq)).
I think it is nessary to make vq_present macro's value only TRUE and FALSE.

arch/arm64/kvm/guest.c
static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
	for (vq = SVE_VQ_MIN; vq <= max_vq; ++vq)
		if (vq_present(vqs, vq) != sve_vq_available(vq))　// It failed at here.
			return -EINVAL;

My patch as follows.
I have started up KVM guest os successfully with SVE feature with this patch.

Could you review and merge my patch?



Signed-off-by: Zhang Lei <zhang.lei@jp.fujitsu.com>
---
 arch/arm64/kvm/guest.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index c2afa79..dfd6264 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -208,7 +208,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)

 #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64)  #define vq_mask(vq) ((u64)1 << ((vq) - SVE_VQ_MIN) % 64) -#define vq_present(vqs, vq) ((vqs)[vq_word(vq)] & vq_mask(vq))
+#define vq_present(vqs, vq) (!!((vqs)[vq_word(vq)] & vq_mask(vq)))

 static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)  {
--
1.8.3.1

> -----Original Message-----
> From: linux-arm-kernel <linux-arm-kernel-bounces@lists.infradead.org> On
> Behalf Of Viresh Kumar
> Sent: Monday, June 10, 2019 7:00 PM
> To: Marc Zyngier <marc.zyngier@arm.com>; James Morse
> <james.morse@arm.com>; Julien Thierry <julien.thierry@arm.com>; Suzuki K
> Pouloze <suzuki.poulose@arm.com>; Catalin Marinas
> <catalin.marinas@arm.com>; Will Deacon <will.deacon@arm.com>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>; linux-kernel@vger.kernel.org;
> kvmarm@lists.cs.columbia.edu; Dave Martin <Dave.Martin@arm.com>;
> linux-arm-kernel@lists.infradead.org
> Subject: [PATCH V3] KVM: arm64: Implement vq_present() as a macro
> 
> This routine is a one-liner and doesn't really need to be function and can be
> implemented as a macro.
> 
> Suggested-by: Dave Martin <Dave.Martin@arm.com>
> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> V2->V3:
> - Pass "vqs" instead of "&vqs" to vq_present().
> - Added Reviewed-by from Dave.
> 
> V1->V2:
> - The previous implementation was fixing a compilation error that
>   occurred only with old compilers (from 2015) due to a bug in the
>   compiler itself.
> 
> - Dave suggested to rather implement this as a macro which made more
>   sense.
> 
>  arch/arm64/kvm/guest.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index
> 3ae2f82fca46..ae734fcfd4ea 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -207,13 +207,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const
> struct kvm_one_reg *reg)
> 
>  #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64)  #define vq_mask(vq)
> ((u64)1 << ((vq) - SVE_VQ_MIN) % 64)
> -
> -static bool vq_present(
> -	const u64 (*const vqs)[KVM_ARM64_SVE_VLS_WORDS],
> -	unsigned int vq)
> -{
> -	return (*vqs)[vq_word(vq)] & vq_mask(vq);
> -}
> +#define vq_present(vqs, vq) ((vqs)[vq_word(vq)] & vq_mask(vq))
> 
>  static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> { @@ -258,7 +252,7 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const
> struct kvm_one_reg *reg)
> 
>  	max_vq = 0;
>  	for (vq = SVE_VQ_MIN; vq <= SVE_VQ_MAX; ++vq)
> -		if (vq_present(&vqs, vq))
> +		if (vq_present(vqs, vq))
>  			max_vq = vq;
> 
>  	if (max_vq > sve_vq_from_vl(kvm_sve_max_vl)) @@ -272,7 +266,7
> @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg
> *reg)
>  	 * maximum:
>  	 */
>  	for (vq = SVE_VQ_MIN; vq <= max_vq; ++vq)
> -		if (vq_present(&vqs, vq) != sve_vq_available(vq))
> +		if (vq_present(vqs, vq) != sve_vq_available(vq))
>  			return -EINVAL;
> 
>  	/* Can't run with no vector lengths at all: */
> --
> 2.21.0.rc0.269.g1a574e7a288b
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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Re: [PATCH V3] KVM: arm64: Implement vq_present() as a macro

[Dave Martin]

On Wed, Jul 03, 2019 at 12:04:11PM +0000, Zhang, Lei wrote:
> Hi guys,
> 
> I can't start up KVM guest os with SVE feature with your patch.
> The error message is 
> qemu-system-aarch64: kvm_init_vcpu failed: Invalid argument.
> 
> My test enviroment.
> kernel  linux-5.2-rc6
> qemu  [Qemu-devel] [PATCH v2 00/14] target/arm/kvm: enable SVE in guests https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04945.html
> KVM start up option
> -machine virt,gic-version=host,accel=kvm \
> -cpu host \
> -machine type=virt \
> -nographic \
> -smp 16 \ -m 4096 \
> -drive if=none,file=/root/image.qcow2,id=hd0,format=qcow2 \
> -device virtio-blk-device,drive=hd0 \
> -netdev user,id=mynet0,restrict=off,hostfwd=tcp::38001-:22 \
> -device virtio-net-device,netdev=mynet0 \
> -bios /root/QEMU_EFI.fd
> 
> sve_vq_available function's return value' type is bool.
> But vq_present is macro, so the value is not only TRUE, FALSE but also some numbers.
> So It failed at 
> if (vq_present(vqs, vq) != sve_vq_available(vq)).
> I think it is nessary to make vq_present macro's value only TRUE and FALSE.
> 
> arch/arm64/kvm/guest.c
> static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> 	for (vq = SVE_VQ_MIN; vq <= max_vq; ++vq)
> 		if (vq_present(vqs, vq) != sve_vq_available(vq))　// It failed at here.
> 			return -EINVAL;
> 
> My patch as follows.
> I have started up KVM guest os successfully with SVE feature with this patch.
> 
> Could you review and merge my patch?

[...]

Thanks for reporting this!  It looks like we didn't realise we dropped
the implicit cast to bool when the result was returned from the original
version of vq_present().

Your fix looks sensible to me.

For the future, see Documentation/process/submitting-patches.rst for
guidance on how to prepare a patch for submission.

However, due to the fact that we're already at -rc7 I've written a
commit message for the patch and reposted [1].  Since the fix is yours,
I'll keep your authorship and S-o-B.

Please retest when you can (though the diff should be the same).

Note, your mail seems to be corrupted, but since the diff is a one-line
fix, I'm pretty confident I decoded it correctly.  If anything looks
wrong, please let me know.

[...]

Cheers
---Dave


[1] [PATCH] KVM: arm64/sve: Fix vq_present() macro to yield a bool
http://lists.infradead.org/pipermail/linux-arm-kernel/2019-July/664745.html
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