Subject: Re: [PATCH v2 02/16] KVM: PPC: Book3S HV: add a new KVM device for the XIVE native exploitation mode

From: David Gibson <[email-masked]>
Date: Mon, 25 Feb 2019 11:08:48 +1100

On Fri, Feb 22, 2019 at 12:28:26PM +0100, Cédric Le Goater wrote:
> This is the basic framework for the new KVM device supporting the XIVE
> native exploitation mode. The user interface exposes a new KVM device
> to be created by QEMU when running on a L0 hypervisor only. Support
> for nested guests is not available yet.
> 
> Signed-off-by: Cédric Le Goater <[email-masked]>
> ---
>  arch/powerpc/include/asm/kvm_host.h        |   1 +
>  arch/powerpc/include/asm/kvm_ppc.h         |   8 +
>  arch/powerpc/include/uapi/asm/kvm.h        |   3 +
>  include/uapi/linux/kvm.h                   |   2 +
>  arch/powerpc/kvm/book3s.c                  |   7 +-
>  arch/powerpc/kvm/book3s_xive_native.c      | 191 +++++++++++++++++++++
>  Documentation/virtual/kvm/devices/xive.txt |  19 ++
>  arch/powerpc/kvm/Makefile                  |   2 +-
>  8 files changed, 231 insertions(+), 2 deletions(-)
>  create mode 100644 arch/powerpc/kvm/book3s_xive_native.c
>  create mode 100644 Documentation/virtual/kvm/devices/xive.txt
> 
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 091430339db1..9f75a75a07f2 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -220,6 +220,7 @@ extern struct kvm_device_ops kvm_xics_ops;
>  struct kvmppc_xive;
>  struct kvmppc_xive_vcpu;
>  extern struct kvm_device_ops kvm_xive_ops;
> +extern struct kvm_device_ops kvm_xive_native_ops;
>  
>  struct kvmppc_passthru_irqmap;
>  
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index b3bf4f61b30c..4b72ddde7dc1 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -593,6 +593,10 @@ extern int kvmppc_xive_set_icp(struct kvm_vcpu *vcpu, u64 icpval);
>  extern int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq,
>  			       int level, bool line_status);
>  extern void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu);
> +
> +extern void kvmppc_xive_native_init_module(void);
> +extern void kvmppc_xive_native_exit_module(void);
> +
>  #else
>  static inline int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 server,
>  				       u32 priority) { return -1; }
> @@ -616,6 +620,10 @@ static inline int kvmppc_xive_set_icp(struct kvm_vcpu *vcpu, u64 icpval) { retur
>  static inline int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq,
>  				      int level, bool line_status) { return -ENODEV; }
>  static inline void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu) { }
> +
> +static inline void kvmppc_xive_native_init_module(void) { }
> +static inline void kvmppc_xive_native_exit_module(void) { }
> +
>  #endif /* CONFIG_KVM_XIVE */
>  
>  #ifdef CONFIG_PPC_POWERNV
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index 8c876c166ef2..b002c0c67787 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -675,4 +675,7 @@ struct kvm_ppc_cpu_char {
>  #define  KVM_XICS_PRESENTED		(1ULL << 43)
>  #define  KVM_XICS_QUEUED		(1ULL << 44)
>  
> +/* POWER9 XIVE Native Interrupt Controller */
> +#define KVM_DEV_XIVE_GRP_CTRL		1
> +
>  #endif /* __LINUX_KVM_POWERPC_H */
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 6d4ea4b6c922..e6368163d3a0 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1211,6 +1211,8 @@ enum kvm_device_type {
>  #define KVM_DEV_TYPE_ARM_VGIC_V3	KVM_DEV_TYPE_ARM_VGIC_V3
>  	KVM_DEV_TYPE_ARM_VGIC_ITS,
>  #define KVM_DEV_TYPE_ARM_VGIC_ITS	KVM_DEV_TYPE_ARM_VGIC_ITS
> +	KVM_DEV_TYPE_XIVE,
> +#define KVM_DEV_TYPE_XIVE		KVM_DEV_TYPE_XIVE
>  	KVM_DEV_TYPE_MAX,
>  };
>  
> diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
> index 601c094f15ab..96d43f091255 100644
> --- a/arch/powerpc/kvm/book3s.c
> +++ b/arch/powerpc/kvm/book3s.c
> @@ -1040,6 +1040,9 @@ static int kvmppc_book3s_init(void)
>  	if (xics_on_xive()) {
>  		kvmppc_xive_init_module();
>  		kvm_register_device_ops(&kvm_xive_ops, KVM_DEV_TYPE_XICS);
> +		kvmppc_xive_native_init_module();
> +		kvm_register_device_ops(&kvm_xive_native_ops,
> +					KVM_DEV_TYPE_XIVE);
>  	} else
>  #endif
>  		kvm_register_device_ops(&kvm_xics_ops, KVM_DEV_TYPE_XICS);
> @@ -1050,8 +1053,10 @@ static int kvmppc_book3s_init(void)
>  static void kvmppc_book3s_exit(void)
>  {
>  #ifdef CONFIG_KVM_XICS
> -	if (xics_on_xive())
> +	if (xics_on_xive()) {
>  		kvmppc_xive_exit_module();
> +		kvmppc_xive_native_exit_module();
> +	}
>  #endif
>  #ifdef CONFIG_KVM_BOOK3S_32_HANDLER
>  	kvmppc_book3s_exit_pr();
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
> new file mode 100644
> index 000000000000..e475ce83ad14
> --- /dev/null
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -0,0 +1,191 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2017-2019, IBM Corporation.
> + */
> +
> +#define pr_fmt(fmt) "xive-kvm: " fmt
> +
> +#include <linux/anon_inodes.h>
> +#include <linux/kernel.h>
> +#include <linux/kvm_host.h>
> +#include <linux/err.h>
> +#include <linux/gfp.h>
> +#include <linux/spinlock.h>
> +#include <linux/delay.h>
> +#include <linux/percpu.h>
> +#include <linux/cpumask.h>
> +#include <asm/uaccess.h>
> +#include <asm/kvm_book3s.h>
> +#include <asm/kvm_ppc.h>
> +#include <asm/hvcall.h>
> +#include <asm/xics.h>
> +#include <asm/xive.h>
> +#include <asm/xive-regs.h>
> +#include <asm/debug.h>
> +#include <asm/debugfs.h>
> +#include <asm/time.h>
> +#include <asm/opal.h>
> +
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> +
> +#include "book3s_xive.h"
> +
> +static int kvmppc_xive_native_set_attr(struct kvm_device *dev,
> +				       struct kvm_device_attr *attr)
> +{
> +	switch (attr->group) {
> +	case KVM_DEV_XIVE_GRP_CTRL:
> +		break;
> +	}
> +	return -ENXIO;
> +}
> +
> +static int kvmppc_xive_native_get_attr(struct kvm_device *dev,
> +				       struct kvm_device_attr *attr)
> +{
> +	return -ENXIO;
> +}
> +
> +static int kvmppc_xive_native_has_attr(struct kvm_device *dev,
> +				       struct kvm_device_attr *attr)
> +{
> +	switch (attr->group) {
> +	case KVM_DEV_XIVE_GRP_CTRL:
> +		break;
> +	}
> +	return -ENXIO;
> +}
> +
> +static void kvmppc_xive_native_free(struct kvm_device *dev)
> +{
> +	struct kvmppc_xive *xive = dev->private;
> +	struct kvm *kvm = xive->kvm;
> +
> +	debugfs_remove(xive->dentry);
> +
> +	pr_devel("Destroying xive native device\n");
> +
> +	if (kvm)
> +		kvm->arch.xive = NULL;
> +
> +	if (xive->vp_base != XIVE_INVALID_VP)
> +		xive_native_free_vp_block(xive->vp_base);
> +
> +	kfree(xive);
> +	kfree(dev);
> +}
> +
> +static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
> +{
> +	struct kvmppc_xive *xive;
> +	struct kvm *kvm = dev->kvm;
> +	int ret = 0;
> +
> +	pr_devel("Creating xive native device\n");
> +
> +	if (kvm->arch.xive)
> +		return -EEXIST;
> +
> +	xive = kzalloc(sizeof(*xive), GFP_KERNEL);
> +	if (!xive)
> +		return -ENOMEM;
> +
> +	dev->private = xive;
> +	xive->dev = dev;
> +	xive->kvm = kvm;
> +	kvm->arch.xive = xive;
> +
> +	/* We use the default queue size set by the host */

IIUC the queue is examined directly by the guest, so the guest must
know its size.  In which case letting the host decide the size would
be a problem for migration.

> +	xive->q_order = xive_native_default_eq_shift();
> +	if (xive->q_order < PAGE_SHIFT)
> +		xive->q_page_order = 0;
> +	else
> +		xive->q_page_order = xive->q_order - PAGE_SHIFT;
> +
> +	/*
> +	 * Allocate a bunch of VPs. KVM_MAX_VCPUS is a large value for
> +	 * a default. Getting the max number of CPUs the VM was
> +	 * configured with would improve our usage of the XIVE VP space.
> +	 */
> +	xive->vp_base = xive_native_alloc_vp_block(KVM_MAX_VCPUS);
> +	pr_devel("VP_Base=%x\n", xive->vp_base);
> +
> +	if (xive->vp_base == XIVE_INVALID_VP)
> +		ret = -ENOMEM;
> +
> +	xive->single_escalation = xive_native_has_single_escalation();
> +
> +	if (ret)
> +		kfree(xive);
> +
> +	return ret;
> +}
> +
> +static int xive_native_debug_show(struct seq_file *m, void *private)
> +{
> +	struct kvmppc_xive *xive = m->private;
> +	struct kvm *kvm = xive->kvm;
> +
> +	if (!kvm)
> +		return 0;
> +
> +	return 0;
> +}
> +
> +static int xive_native_debug_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, xive_native_debug_show, inode->i_private);
> +}
> +
> +static const struct file_operations xive_native_debug_fops = {
> +	.open = xive_native_debug_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +};
> +
> +static void xive_native_debugfs_init(struct kvmppc_xive *xive)
> +{
> +	char *name;
> +
> +	name = kasprintf(GFP_KERNEL, "kvm-xive-%p", xive);
> +	if (!name) {
> +		pr_err("%s: no memory for name\n", __func__);
> +		return;
> +	}
> +
> +	xive->dentry = debugfs_create_file(name, 0444, powerpc_debugfs_root,
> +					   xive, &xive_native_debug_fops);
> +
> +	pr_debug("%s: created %s\n", __func__, name);
> +	kfree(name);
> +}
> +
> +static void kvmppc_xive_native_init(struct kvm_device *dev)
> +{
> +	struct kvmppc_xive *xive = (struct kvmppc_xive *)dev->private;
> +
> +	/* Register some debug interfaces */
> +	xive_native_debugfs_init(xive);
> +}
> +
> +struct kvm_device_ops kvm_xive_native_ops = {
> +	.name = "kvm-xive-native",
> +	.create = kvmppc_xive_native_create,
> +	.init = kvmppc_xive_native_init,
> +	.destroy = kvmppc_xive_native_free,
> +	.set_attr = kvmppc_xive_native_set_attr,
> +	.get_attr = kvmppc_xive_native_get_attr,
> +	.has_attr = kvmppc_xive_native_has_attr,
> +};
> +
> +void kvmppc_xive_native_init_module(void)
> +{
> +	;
> +}
> +
> +void kvmppc_xive_native_exit_module(void)
> +{
> +	;
> +}
> diff --git a/Documentation/virtual/kvm/devices/xive.txt b/Documentation/virtual/kvm/devices/xive.txt
> new file mode 100644
> index 000000000000..fdbd2ff92a88
> --- /dev/null
> +++ b/Documentation/virtual/kvm/devices/xive.txt
> @@ -0,0 +1,19 @@
> +POWER9 eXternal Interrupt Virtualization Engine (XIVE Gen1)
> +==========================================================
> +
> +Device types supported:
> +  KVM_DEV_TYPE_XIVE     POWER9 XIVE Interrupt Controller generation 1
> +
> +This device acts as a VM interrupt controller. It provides the KVM
> +interface to configure the interrupt sources of a VM in the underlying
> +POWER9 XIVE interrupt controller.
> +
> +Only one XIVE instance may be instantiated. A guest XIVE device
> +requires a POWER9 host and the guest OS should have support for the
> +XIVE native exploitation interrupt mode. If not, it should run using
> +the legacy interrupt mode, referred as XICS (POWER7/8).
> +
> +* Groups:
> +
> +  1. KVM_DEV_XIVE_GRP_CTRL
> +  Provides global controls on the device
> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
> index 64f1135e7732..806cbe488410 100644
> --- a/arch/powerpc/kvm/Makefile
> +++ b/arch/powerpc/kvm/Makefile
> @@ -99,7 +99,7 @@ endif
>  kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \
>  	book3s_xics.o
>  
> -kvm-book3s_64-objs-$(CONFIG_KVM_XIVE) += book3s_xive.o
> +kvm-book3s_64-objs-$(CONFIG_KVM_XIVE) += book3s_xive.o book3s_xive_native.o
>  kvm-book3s_64-objs-$(CONFIG_SPAPR_TCE_IOMMU) += book3s_64_vio.o
>  
>  kvm-book3s_64-module-objs := \

-- 
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