On Fri, Feb 22, 2019 at 12:28:34PM +0100, Cédric Le Goater wrote:
> At a VCPU level, the state of the thread interrupt management
> registers needs to be collected. These registers are cached under the
> 'xive_saved_state.w01' field of the VCPU when the VPCU context is
> pulled from the HW thread. An OPAL call retrieves the backup of the
> IPB register in the underlying XIVE NVT structure and merges it in the
> KVM state.
>
> The structures of the interface between QEMU and KVM provisions some
> extra room (two u64) for further extensions if more state needs to be
> transferred back to QEMU.
>
> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 11 +++
> arch/powerpc/include/uapi/asm/kvm.h | 2 +
> arch/powerpc/kvm/book3s.c | 24 +++++++
> arch/powerpc/kvm/book3s_xive_native.c | 82 ++++++++++++++++++++++
> Documentation/virtual/kvm/devices/xive.txt | 19 +++++
> 5 files changed, 138 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h
> b/arch/powerpc/include/asm/kvm_ppc.h
> index 1e61877fe147..664c65051612 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -272,6 +272,7 @@ union kvmppc_one_reg {
> u64 addr;
> u64 length;
> } vpaval;
> + u64 xive_timaval[4];
This is doubling the size of the userspace visible one_reg union. Is
that safe?
> };
>
> struct kvmppc_ops {
> @@ -604,6 +605,10 @@ extern int kvmppc_xive_native_connect_vcpu(struct
> kvm_device *dev,
> extern void kvmppc_xive_native_cleanup_vcpu(struct kvm_vcpu *vcpu);
> extern void kvmppc_xive_native_init_module(void);
> extern void kvmppc_xive_native_exit_module(void);
> +extern int kvmppc_xive_native_get_vp(struct kvm_vcpu *vcpu,
> + union kvmppc_one_reg *val);
> +extern int kvmppc_xive_native_set_vp(struct kvm_vcpu *vcpu,
> + union kvmppc_one_reg *val);
>
> #else
> static inline int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 server,
> @@ -636,6 +641,12 @@ static inline int kvmppc_xive_native_connect_vcpu(struct
> kvm_device *dev,
> static inline void kvmppc_xive_native_cleanup_vcpu(struct kvm_vcpu *vcpu) { }
> static inline void kvmppc_xive_native_init_module(void) { }
> static inline void kvmppc_xive_native_exit_module(void) { }
> +static inline int kvmppc_xive_native_get_vp(struct kvm_vcpu *vcpu,
> + union kvmppc_one_reg *val)
> +{ return 0; }
> +static inline int kvmppc_xive_native_set_vp(struct kvm_vcpu *vcpu,
> + union kvmppc_one_reg *val)
> +{ return -ENOENT; }
>
> #endif /* CONFIG_KVM_XIVE */
>
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h
> b/arch/powerpc/include/uapi/asm/kvm.h
> index cd78ad1020fe..42d4ef93ec2d 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -480,6 +480,8 @@ struct kvm_ppc_cpu_char {
> #define KVM_REG_PPC_ICP_PPRI_SHIFT 16 /* pending irq priority */
> #define KVM_REG_PPC_ICP_PPRI_MASK 0xff
>
> +#define KVM_REG_PPC_VP_STATE (KVM_REG_PPC | KVM_REG_SIZE_U256 | 0x8d)
> +
> /* Device control API: PPC-specific devices */
> #define KVM_DEV_MPIC_GRP_MISC 1
> #define KVM_DEV_MPIC_BASE_ADDR 0 /* 64-bit */
> diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
> index 96d43f091255..f85a9211f30c 100644
> --- a/arch/powerpc/kvm/book3s.c
> +++ b/arch/powerpc/kvm/book3s.c
> @@ -641,6 +641,18 @@ int kvmppc_get_one_reg(struct kvm_vcpu *vcpu, u64 id,
> *val = get_reg_val(id,
> kvmppc_xics_get_icp(vcpu));
> break;
> #endif /* CONFIG_KVM_XICS */
> +#ifdef CONFIG_KVM_XIVE
> + case KVM_REG_PPC_VP_STATE:
> + if (!vcpu->arch.xive_vcpu) {
> + r = -ENXIO;
> + break;
> + }
> + if (xive_enabled())
> + r = kvmppc_xive_native_get_vp(vcpu, val);
> + else
> + r = -ENXIO;
> + break;
> +#endif /* CONFIG_KVM_XIVE */
> case KVM_REG_PPC_FSCR:
> *val = get_reg_val(id, vcpu->arch.fscr);
> break;
> @@ -714,6 +726,18 @@ int kvmppc_set_one_reg(struct kvm_vcpu *vcpu, u64 id,
> r = kvmppc_xics_set_icp(vcpu, set_reg_val(id,
> *val));
> break;
> #endif /* CONFIG_KVM_XICS */
> +#ifdef CONFIG_KVM_XIVE
> + case KVM_REG_PPC_VP_STATE:
> + if (!vcpu->arch.xive_vcpu) {
> + r = -ENXIO;
> + break;
> + }
> + if (xive_enabled())
> + r = kvmppc_xive_native_set_vp(vcpu, val);
> + else
> + r = -ENXIO;
> + break;
> +#endif /* CONFIG_KVM_XIVE */
> case KVM_REG_PPC_FSCR:
> vcpu->arch.fscr = set_reg_val(id, *val);
> break;
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c
> b/arch/powerpc/kvm/book3s_xive_native.c
> index 3debc876d5a0..132bff52d70a 100644
> --- a/arch/powerpc/kvm/book3s_xive_native.c
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -845,6 +845,88 @@ static int kvmppc_xive_native_create(struct kvm_device
> *dev, u32 type)
> return ret;
> }
>
> +/*
> + * Interrupt Pending Buffer (IPB) offset
> + */
> +#define TM_IPB_SHIFT 40
> +#define TM_IPB_MASK (((u64) 0xFF) << TM_IPB_SHIFT)
> +
> +int kvmppc_xive_native_get_vp(struct kvm_vcpu *vcpu, union kvmppc_one_reg
> *val)
> +{
> + struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
> + u64 opal_state;
> + int rc;
> +
> + if (!kvmppc_xive_enabled(vcpu))
> + return -EPERM;
> +
> + if (!xc)
> + return -ENOENT;
> +
> + /* Thread context registers. We only care about IPB and CPPR */
> + val->xive_timaval[0] = vcpu->arch.xive_saved_state.w01;
> +
> + /*
> + * Return the OS CAM line to print out the VP identifier in
> + * the QEMU monitor. This is not restored.
> + */
> + val->xive_timaval[1] = vcpu->arch.xive_cam_word;
I'm pretty dubious about this mixing of vital state information with
what's basically debug information. Doubly so since it requires
changing the ABI to increase the one_reg union's size.
Might be better to have this control only return the 0th and 2nd u64s
from the TIMA, with the CAM debug information returned via some other
mechanism.
> +
> + /* Get the VP state from OPAL */
> + rc = xive_native_get_vp_state(xc->vp_id, &opal_state);
> + if (rc)
> + return rc;
> +
> + /*
> + * Capture the backup of IPB register in the NVT structure and
> + * merge it in our KVM VP state.
> + */
> + val->xive_timaval[0] |= cpu_to_be64(opal_state & TM_IPB_MASK);
> +
> + pr_devel("%s NSR=%02x CPPR=%02x IBP=%02x PIPR=%02x w01=%016llx w2=%08x
> opal=%016llx\n",
> + __func__,
> + vcpu->arch.xive_saved_state.nsr,
> + vcpu->arch.xive_saved_state.cppr,
> + vcpu->arch.xive_saved_state.ipb,
> + vcpu->arch.xive_saved_state.pipr,
> + vcpu->arch.xive_saved_state.w01,
> + (u32) vcpu->arch.xive_cam_word, opal_state);
Hrm.. except you don't seem to be using the last half of the timaval
field anyway.
> +
> + return 0;
> +}
> +
> +int kvmppc_xive_native_set_vp(struct kvm_vcpu *vcpu, union kvmppc_one_reg
> *val)
> +{
> + struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
> + struct kvmppc_xive *xive = vcpu->kvm->arch.xive;
> +
> + pr_devel("%s w01=%016llx vp=%016llx\n", __func__,
> + val->xive_timaval[0], val->xive_timaval[1]);
> +
> + if (!kvmppc_xive_enabled(vcpu))
> + return -EPERM;
> +
> + if (!xc || !xive)
> + return -ENOENT;
> +
> + /* We can't update the state of a "pushed" VCPU */
> + if (WARN_ON(vcpu->arch.xive_pushed))
What prevents userspace from tripping this WARN_ON()?
> + return -EIO;
EBUSY might be more appropriate here.
> +
> + /*
> + * Restore the thread context registers. IPB and CPPR should
> + * be the only ones that matter.
> + */
> + vcpu->arch.xive_saved_state.w01 = val->xive_timaval[0];
> +
> + /*
> + * There is no need to restore the XIVE internal state (IPB
> + * stored in the NVT) as the IPB register was merged in KVM VP
> + * state when captured.
> + */
> + return 0;
> +}
> +
> static int xive_native_debug_show(struct seq_file *m, void *private)
> {
> struct kvmppc_xive *xive = m->private;
> diff --git a/Documentation/virtual/kvm/devices/xive.txt
> b/Documentation/virtual/kvm/devices/xive.txt
> index a26be635cff9..1b8957c50c53 100644
> --- a/Documentation/virtual/kvm/devices/xive.txt
> +++ b/Documentation/virtual/kvm/devices/xive.txt
> @@ -102,6 +102,25 @@ the legacy interrupt mode, referred as XICS (POWER7/8).
> -EINVAL: Not initialized source number, invalid priority or
> invalid CPU number.
>
> +* VCPU state
> +
> + The XIVE IC maintains VP interrupt state in an internal structure
> + called the NVT. When a VP is not dispatched on a HW processor
> + thread, this structure can be updated by HW if the VP is the target
> + of an event notification.
> +
> + It is important for migration to capture the cached IPB from the NVT
> + as it synthesizes the priorities of the pending interrupts. We
> + capture a bit more to report debug information.
> +
> + KVM_REG_PPC_VP_STATE (4 * 64bits)
> + bits: | 63 .... 32 | 31 .... 0 |
> + values: | TIMA word0 | TIMA word1 |
> + bits: | 127 .......... 64 |
> + values: | VP CAM Line |
> + bits: | 255 .......... 128 |
> + values: | unused |
> +
> * Migration:
>
> Saving the state of a VM using the XIVE native exploitation mode
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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