Re: [PATCH] kvmtool: arm64: Report missing support for 32bit guests

2020-07-03 Thread Will Deacon 
On Wed, 1 Jul 2020 15:20:02 +0100, Suzuki K Poulose wrote:
> When the host doesn't support 32bit guests, the kvmtool fails
> without a proper message on what is wrong. i.e,
> 
>  $ lkvm run -c 1 Image --aarch32
>   # lkvm run -k Image -m 256 -c 1 --name guest-105618
>   Fatal: Unable to initialise vcpu
> 
> [...]

Applied to kvmtool (master), thanks!

[1/1] kvmtool: arm64: Report missing support for 32bit guests
  https://git.kernel.org/will/kvmtool/c/351d931f496a

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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Re: [PATCH] kvmtool: arm64: Report missing support for 32bit guests

2020-07-02 Thread Marc Zyngier 

On 2020-07-02 16:37, Suzuki K Poulose wrote:

Hi Marc

On 07/01/2020 04:42 PM, Marc Zyngier wrote:

On 2020-07-01 15:20, Suzuki K Poulose wrote:

When the host doesn't support 32bit guests, the kvmtool fails
without a proper message on what is wrong. i.e,

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105618
  Fatal: Unable to initialise vcpu

Given that there is no other easy way to check if the host supports 
32bit
guests, it is always good to report this by checking the capability, 
rather

than leaving the users to hunt this down by looking at the code!

After this patch:

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105695
  Fatal: 32bit guests are not supported


Fancy!



Cc: Will Deacon 
Reported-by: Sami Mujawar 
Signed-off-by: Suzuki K Poulose 
---
 arm/kvm-cpu.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 554414f..2acecae 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -46,6 +46,10 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm 
*kvm,

unsigned long cpu_id)
 .features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id)
 };

+    if (kvm->cfg.arch.aarch32_guest &&
+    !kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT))


Can you please check that this still compiles for 32bit host?


Yes, it does. I have built this on an arm32 rootfs with make ARCH=arm.
The kvm->cfg.arch is common across arm/arm64 and is defined here :

arm/include/arm-common/kvm-config-arch.h


I was worried about the availability of KVM_CAP_ARM_EL1_32BIT,
but being a capability, it is common to all arches. It is
KVM_ARM_VCPU_EL1_32BIT that is 32bit only, but that's not what
you are using. Too many flags! ;-)

Thanks,

M.
--
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Re: [PATCH] kvmtool: arm64: Report missing support for 32bit guests

2020-07-02 Thread Suzuki K Poulose 

Hi Marc

On 07/01/2020 04:42 PM, Marc Zyngier wrote:

On 2020-07-01 15:20, Suzuki K Poulose wrote:

When the host doesn't support 32bit guests, the kvmtool fails
without a proper message on what is wrong. i.e,

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105618
  Fatal: Unable to initialise vcpu

Given that there is no other easy way to check if the host supports 32bit
guests, it is always good to report this by checking the capability, 
rather

than leaving the users to hunt this down by looking at the code!

After this patch:

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105695
  Fatal: 32bit guests are not supported


Fancy!



Cc: Will Deacon 
Reported-by: Sami Mujawar 
Signed-off-by: Suzuki K Poulose 
---
 arm/kvm-cpu.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 554414f..2acecae 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -46,6 +46,10 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm,
unsigned long cpu_id)
 .features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id)
 };

+    if (kvm->cfg.arch.aarch32_guest &&
+    !kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT))


Can you please check that this still compiles for 32bit host?


Yes, it does. I have built this on an arm32 rootfs with make ARCH=arm.
The kvm->cfg.arch is common across arm/arm64 and is defined here :

arm/include/arm-common/kvm-config-arch.h

And the aarch32 command line option is only available on aarch64 host.
So this is safe on an arm32 host.




+    die("32bit guests are not supported\n");
+
 vcpu = calloc(1, sizeof(struct kvm_cpu));
 if (!vcpu)
 return NULL;


With the above detail checked,

Acked-by: Marc Zyngier 


Thanks
Suzuki
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Re: [PATCH] kvmtool: arm64: Report missing support for 32bit guests

2020-07-01 Thread Marc Zyngier 

On 2020-07-01 15:20, Suzuki K Poulose wrote:

When the host doesn't support 32bit guests, the kvmtool fails
without a proper message on what is wrong. i.e,

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105618
  Fatal: Unable to initialise vcpu

Given that there is no other easy way to check if the host supports 
32bit
guests, it is always good to report this by checking the capability, 
rather

than leaving the users to hunt this down by looking at the code!

After this patch:

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105695
  Fatal: 32bit guests are not supported


Fancy!



Cc: Will Deacon 
Reported-by: Sami Mujawar 
Signed-off-by: Suzuki K Poulose 
---
 arm/kvm-cpu.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 554414f..2acecae 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -46,6 +46,10 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm,
unsigned long cpu_id)
.features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id)
};

+   if (kvm->cfg.arch.aarch32_guest &&
+   !kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT))


Can you please check that this still compiles for 32bit host?


+   die("32bit guests are not supported\n");
+
vcpu = calloc(1, sizeof(struct kvm_cpu));
if (!vcpu)
return NULL;


With the above detail checked,

Acked-by: Marc Zyngier 

M.
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[PATCH] kvmtool: arm64: Report missing support for 32bit guests

2020-07-01 Thread Suzuki K Poulose 
When the host doesn't support 32bit guests, the kvmtool fails
without a proper message on what is wrong. i.e,

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105618
  Fatal: Unable to initialise vcpu

Given that there is no other easy way to check if the host supports 32bit
guests, it is always good to report this by checking the capability, rather
than leaving the users to hunt this down by looking at the code!

After this patch:

 $ lkvm run -c 1 Image --aarch32
  # lkvm run -k Image -m 256 -c 1 --name guest-105695
  Fatal: 32bit guests are not supported

Cc: Will Deacon 
Reported-by: Sami Mujawar 
Signed-off-by: Suzuki K Poulose 
---
 arm/kvm-cpu.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 554414f..2acecae 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -46,6 +46,10 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned 
long cpu_id)
.features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id)
};
 
+   if (kvm->cfg.arch.aarch32_guest &&
+   !kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT))
+   die("32bit guests are not supported\n");
+
vcpu = calloc(1, sizeof(struct kvm_cpu));
if (!vcpu)
return NULL;
-- 
2.24.1

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