| Message ID | 20200701142002.51654-1-suzuki.poulose@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kvmtool: arm64: Report missing support for 32bit guests | expand |
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 <will@kernel.org> > Reported-by: Sami Mujawar <sami.mujawar@arm.com> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > 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 <maz@kernel.org> M.
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 <will@kernel.org> >> Reported-by: Sami Mujawar <sami.mujawar@arm.com> >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >> --- >> 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 <maz@kernel.org> Thanks Suzuki
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 <will@kernel.org> >>> Reported-by: Sami Mujawar <sami.mujawar@arm.com> >>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >>> --- >>> 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.
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,
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;
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 <will@kernel.org> Reported-by: Sami Mujawar <sami.mujawar@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- arm/kvm-cpu.c | 4 ++++ 1 file changed, 4 insertions(+)