| Message ID | 1448968304-10128-1-git-send-email-p.fedin@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 01, 2015 at 02:11:44PM +0300, Pavel Fedin wrote: > Before commit 662d9715840aef44dcb573b0f9fab9e8319c868a > ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}") is was possible to > compile the kernel without vGIC and vTimer support. Commit message says > about possibility to detect vGIC support in runtime, but this has never > been implemented. > > This patch introdices runtime check, restoring the lost functionality. introduces > It again allows to use KVM on hardware without vGIC. Interrupt > controller has to be emulated in userspace in this case. > > -ENODEV return code from probe function means there's no GIC at all. > -ENXIO happens when, for example, there is GIC node in the device tree, > but it does not specify vGIC resources. Normally this means that vGIC > hardware is defunct. Any other error code is still treated as full stop drop the "Normally this means" sentence. > because it might mean some really serious problems. > > This patch does not touch any virtual timer code, suggesting that timer > hardware is actually in place. Normally on boards in question it is true, > however since vGIC is missing, it is impossible to correctly utilize > interrupts from the virtual timer. Since virtual timer handling is in > active redevelopment now, handling in it userspace is out of scope at > the moment. The guest is currently suggested to use some memory-mapped > timer which can be emulated in userspace. Not sure I understand this paragraph. Either drop it or just say "The architectured timers are not supported without the in-kernel vGIC." > > Signed-off-by: Pavel Fedin <p.fedin@samsung.com> > --- > v5 => v6: > - KVM_CAP_IRQFD patch also dropped, causing many problems on PowerPC and > S390 > - Rebased on top of 4.3-rc3 > > v4 => v5: > - Tested on top of kvmarm/next > - Dropped already applied part > - Fixed minor checkpatch issues > > v3 => v4: > - Revert back to using switch on kvm_vgic_hyp_init() return code. I decided > to leave 'vgic_present = false' statement because it helps to understand > the code. > > v2 => v3: > - Improved commit messages, added references to commits where the respective > functionality was broken > - Explicitly specify that the solution currently affects only vGIC and has > nothing to do with timer. > - Fixed code style according to previous notes > - Removed ARM64 save/restore patch introduced in v2 because it was already > obsolete for linux-next > - Modify KVM_CAP_IRQFD handling in correct place > > v1 => v2: > - Do not use defensive approach in patch 0001. Use correct conditions in > callers instead > - Added ARM64-specific code, without which attempt to run a VM ends in a > HYP crash because of unset vGIC save/restore function pointers > --- > arch/arm/kvm/arm.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index e06fd29..66f90c1 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -61,6 +61,8 @@ static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1); > static u8 kvm_next_vmid; > static DEFINE_SPINLOCK(kvm_vmid_lock); > > +static bool vgic_present; > + > static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu) > { > BUG_ON(preemptible()); > @@ -132,7 +134,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > kvm->arch.vmid_gen = 0; > > /* The maximum number of VCPUs is limited by the host's GIC model */ > - kvm->arch.max_vcpus = kvm_vgic_get_max_vcpus(); > + kvm->arch.max_vcpus = vgic_present ? > + kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; > > return ret; > out_free_stage2_pgd: > @@ -172,6 +175,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > int r; > switch (ext) { > case KVM_CAP_IRQCHIP: > + r = vgic_present; > + break; > case KVM_CAP_IOEVENTFD: > case KVM_CAP_DEVICE_CTRL: > case KVM_CAP_USER_MEMORY: > @@ -913,6 +918,8 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, > > switch (dev_id) { > case KVM_ARM_DEVICE_VGIC_V2: > + if (!vgic_present) > + return -ENXIO; > return kvm_vgic_addr(kvm, type, &dev_addr->addr, true); > default: > return -ENODEV; > @@ -927,6 +934,8 @@ long kvm_arch_vm_ioctl(struct file *filp, > > switch (ioctl) { > case KVM_CREATE_IRQCHIP: { > + if (!vgic_present) > + return -ENXIO; > return kvm_vgic_create(kvm, KVM_DEV_TYPE_ARM_VGIC_V2); > } > case KVM_ARM_SET_DEVICE_ADDR: { > @@ -1111,8 +1120,17 @@ static int init_hyp_mode(void) > * Init HYP view of VGIC > */ > err = kvm_vgic_hyp_init(); > - if (err) > + switch (err) { > + case 0: > + vgic_present = true; > + break; > + case -ENODEV: > + case -ENXIO: > + vgic_present = false; > + break; > + default: > goto out_free_context; > + } > > /* > * Init HYP architected timer support > -- > 2.4.4 > Assuming the commit message gets a bit of love: Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello! > > This patch does not touch any virtual timer code, suggesting that timer > > hardware is actually in place. Normally on boards in question it is true, > > however since vGIC is missing, it is impossible to correctly utilize > > interrupts from the virtual timer. Since virtual timer handling is in > > active redevelopment now, handling in it userspace is out of scope at > > the moment. The guest is currently suggested to use some memory-mapped > > timer which can be emulated in userspace. > > Not sure I understand this paragraph. Either drop it or just say "The > architectured timers are not supported without the in-kernel vGIC." Ok, i'll repost with changed message. But, just to let you know, with this (http://www.spinics.net/lists/kvm/msg124539.html) the notice about architected timer loses its relevancy at all. So, i'll just drop it. Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index e06fd29..66f90c1 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -61,6 +61,8 @@ static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1); static u8 kvm_next_vmid; static DEFINE_SPINLOCK(kvm_vmid_lock); +static bool vgic_present; + static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu) { BUG_ON(preemptible()); @@ -132,7 +134,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.vmid_gen = 0; /* The maximum number of VCPUs is limited by the host's GIC model */ - kvm->arch.max_vcpus = kvm_vgic_get_max_vcpus(); + kvm->arch.max_vcpus = vgic_present ? + kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; return ret; out_free_stage2_pgd: @@ -172,6 +175,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) int r; switch (ext) { case KVM_CAP_IRQCHIP: + r = vgic_present; + break; case KVM_CAP_IOEVENTFD: case KVM_CAP_DEVICE_CTRL: case KVM_CAP_USER_MEMORY: @@ -913,6 +918,8 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, switch (dev_id) { case KVM_ARM_DEVICE_VGIC_V2: + if (!vgic_present) + return -ENXIO; return kvm_vgic_addr(kvm, type, &dev_addr->addr, true); default: return -ENODEV; @@ -927,6 +934,8 @@ long kvm_arch_vm_ioctl(struct file *filp, switch (ioctl) { case KVM_CREATE_IRQCHIP: { + if (!vgic_present) + return -ENXIO; return kvm_vgic_create(kvm, KVM_DEV_TYPE_ARM_VGIC_V2); } case KVM_ARM_SET_DEVICE_ADDR: { @@ -1111,8 +1120,17 @@ static int init_hyp_mode(void) * Init HYP view of VGIC */ err = kvm_vgic_hyp_init(); - if (err) + switch (err) { + case 0: + vgic_present = true; + break; + case -ENODEV: + case -ENXIO: + vgic_present = false; + break; + default: goto out_free_context; + } /* * Init HYP architected timer support
Before commit 662d9715840aef44dcb573b0f9fab9e8319c868a ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}") is was possible to compile the kernel without vGIC and vTimer support. Commit message says about possibility to detect vGIC support in runtime, but this has never been implemented. This patch introdices runtime check, restoring the lost functionality. It again allows to use KVM on hardware without vGIC. Interrupt controller has to be emulated in userspace in this case. -ENODEV return code from probe function means there's no GIC at all. -ENXIO happens when, for example, there is GIC node in the device tree, but it does not specify vGIC resources. Normally this means that vGIC hardware is defunct. Any other error code is still treated as full stop because it might mean some really serious problems. This patch does not touch any virtual timer code, suggesting that timer hardware is actually in place. Normally on boards in question it is true, however since vGIC is missing, it is impossible to correctly utilize interrupts from the virtual timer. Since virtual timer handling is in active redevelopment now, handling in it userspace is out of scope at the moment. The guest is currently suggested to use some memory-mapped timer which can be emulated in userspace. Signed-off-by: Pavel Fedin <p.fedin@samsung.com> --- v5 => v6: - KVM_CAP_IRQFD patch also dropped, causing many problems on PowerPC and S390 - Rebased on top of 4.3-rc3 v4 => v5: - Tested on top of kvmarm/next - Dropped already applied part - Fixed minor checkpatch issues v3 => v4: - Revert back to using switch on kvm_vgic_hyp_init() return code. I decided to leave 'vgic_present = false' statement because it helps to understand the code. v2 => v3: - Improved commit messages, added references to commits where the respective functionality was broken - Explicitly specify that the solution currently affects only vGIC and has nothing to do with timer. - Fixed code style according to previous notes - Removed ARM64 save/restore patch introduced in v2 because it was already obsolete for linux-next - Modify KVM_CAP_IRQFD handling in correct place v1 => v2: - Do not use defensive approach in patch 0001. Use correct conditions in callers instead - Added ARM64-specific code, without which attempt to run a VM ends in a HYP crash because of unset vGIC save/restore function pointers --- arch/arm/kvm/arm.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)