Re: [RFC 07/10] KVM: add KVM TMEM host side interface

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Jun 06, 2012 at 01:00:15PM +0200, Sasha Levin wrote:
> This is the host side interface that the guests which support KVM TMEM
> talk to.
> 
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
>  arch/x86/kvm/tmem/Kconfig            |    6 +++
>  arch/x86/kvm/tmem/Makefile           |    2 +
>  arch/x86/kvm/tmem/host.c             |   78 ++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/tmem/host.h             |   20 +++++++++
>  arch/x86/kvm/x86.c                   |    8 +---
>  drivers/staging/zcache/zcache-main.c |   35 +++++++++++++++-
>  6 files changed, 141 insertions(+), 8 deletions(-)
>  create mode 100644 arch/x86/kvm/tmem/host.c
>  create mode 100644 arch/x86/kvm/tmem/host.h
> 
> diff --git a/arch/x86/kvm/tmem/Kconfig b/arch/x86/kvm/tmem/Kconfig
> index 15d8301..1a59e4f 100644
> --- a/arch/x86/kvm/tmem/Kconfig
> +++ b/arch/x86/kvm/tmem/Kconfig
> @@ -13,4 +13,10 @@ menuconfig KVM_TMEM
>  
>  if KVM_TMEM
>  
> +config KVM_TMEM_HOST
> +	bool "Host-side KVM TMEM"
> +	---help---
> +	With this option on, the KVM host will be able to process KVM TMEM requests
> +	coming from guests.
> +
>  endif # KVM_TMEM
> diff --git a/arch/x86/kvm/tmem/Makefile b/arch/x86/kvm/tmem/Makefile
> index 6812d46..706cd36 100644
> --- a/arch/x86/kvm/tmem/Makefile
> +++ b/arch/x86/kvm/tmem/Makefile
> @@ -1 +1,3 @@
>  ccflags-y += -Idrivers/staging/zcache/
> +
> +obj-$(CONFIG_KVM_TMEM_HOST)			+= host.o
> diff --git a/arch/x86/kvm/tmem/host.c b/arch/x86/kvm/tmem/host.c
> new file mode 100644
> index 0000000..9e73395
> --- /dev/null
> +++ b/arch/x86/kvm/tmem/host.c
> @@ -0,0 +1,78 @@
> +/*
> + * KVM TMEM host side interface
> + *
> + * Copyright (c) 2012 Sasha Levin
> + *
> + */
> +
> +#include <linux/kvm_types.h>
> +#include <linux/kvm_host.h>
> +
> +#include "tmem.h"
> +#include <zcache.h>
> +
> +int use_kvm_tmem_host = 1;

__mostly_read and bool

> +
> +static int no_kvmtmemhost(char *s)
> +{
> +	use_kvm_tmem_host = 0;
> +	return 1;
> +}
> +
> +__setup("nokvmtmemhost", no_kvmtmemhost);
> +
> +int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret)
> +{
> +	struct tmem_kvm_op op;
> +	struct page *page;
> +	int r;
> +	unsigned long flags;
> +
> +	if (!use_kvm_tmem_host || !zcache_enabled) {
> +		*ret = -ENXIO;
> +		return 0;
> +	}
> +
> +	r = kvm_read_guest(vcpu->kvm, addr, &op, sizeof(op));
> +	if (r < 0) {
> +		*ret = r;
> +		return 0;

Shouldn't this return r?

> +	}
> +
> +	switch (op.cmd) {
> +	case TMEM_NEW_POOL:
> +		*ret = zcache_new_pool(op.cli_id, op.u.new.flags);
> +		break;
> +	case TMEM_DESTROY_POOL:
> +		*ret = zcache_destroy_pool(op.cli_id, op.pool_id);
> +		break;
> +	case TMEM_NEW_PAGE:
> +		break;
> +	case TMEM_PUT_PAGE:
> +		page = gfn_to_page(vcpu->kvm, op.u.gen.gfn);
> +		local_irq_save(flags);
> +		*ret = zcache_put_page(op.cli_id, op.pool_id,
> +				&op.u.gen.oid, op.u.gen.index, page);
> +		local_irq_restore(flags);
> +		break;
> +	case TMEM_GET_PAGE:
> +		page = gfn_to_page(vcpu->kvm, op.u.gen.gfn);
> +		local_irq_save(flags);
> +		*ret = zcache_get_page(op.cli_id, op.pool_id,
> +			&op.u.gen.oid, op.u.gen.index, page);
> +		local_irq_restore(flags);
> +		break;
> +	case TMEM_FLUSH_PAGE:
> +		local_irq_save(flags);
> +		*ret = zcache_flush_page(op.cli_id, op.pool_id,
> +				&op.u.gen.oid, op.u.gen.index);
> +		local_irq_restore(flags);
> +		break;
> +	case TMEM_FLUSH_OBJECT:
> +		local_irq_save(flags);
> +		*ret = zcache_flush_object(op.cli_id, op.pool_id, &op.u.gen.oid);
> +		local_irq_restore(flags);
> +		break;
> +	}
> +	return 0;
> +}
> diff --git a/arch/x86/kvm/tmem/host.h b/arch/x86/kvm/tmem/host.h
> new file mode 100644
> index 0000000..17ba0c4
> --- /dev/null
> +++ b/arch/x86/kvm/tmem/host.h
> @@ -0,0 +1,20 @@
> +#ifndef _KVM_TMEM_HOST_H_
> +#define _KVM_TMEM_HOST_H_
> +
> +#ifdef CONFIG_KVM_TMEM_HOST
> +
> +extern int use_kvm_tmem_host;
> +
> +extern int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret);
> +
> +#else
> +
> +static inline int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret)
> +{
> +	*ret = -ENOSUPP;
> +	return 0;
> +}
> +
> +#endif
> +
> +#endif
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 4c5b6ab..c92d4c8 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -27,6 +27,7 @@
>  #include "kvm_cache_regs.h"
>  #include "x86.h"
>  #include "cpuid.h"
> +#include "tmem/host.h"
>  
>  #include <linux/clocksource.h>
>  #include <linux/interrupt.h>
> @@ -4993,13 +4994,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  	return 1;
>  }
>  
> -static int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret)
> -{
> -	*ret = -ENOTSUPP;
> -
> -	return 0;
> -}
> -
>  static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
>  				unsigned long a1)
>  {
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index a196aff..65c0ab0 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -1692,7 +1692,7 @@ out:
>  	return ret;
>  }
>  
> -static int zcache_new_pool(uint16_t cli_id, uint32_t flags)
> +int zcache_new_pool(uint16_t cli_id, uint32_t flags)
>  {
>  	int poolid = -1;
>  	struct tmem_pool *pool;
> @@ -2011,6 +2011,37 @@ out:
>  	return ret;
>  }
>  
> +#ifdef CONFIG_KVM_TMEM_HOST
> +extern int use_kvm_tmem_host;
> +
> +static int __zcache_init_kvm(void)
> +{
> +	int ret = 0;
> +
> +	if (use_kvm_tmem_host) {
> +		ret = zcache_new_client(KVM_CLIENT);
> +		if (ret) {
> +			pr_err("zcache: can't create client\n");
> +			return -1;
> +		} else {
> +			pr_info("zcache: enabled support for KVM TMEM\n");
> +		}
> +	}
> +	zbud_init();
> +	register_shrinker(&zcache_shrinker);
> +
> +	return 0;
> +}
> +
> +#else
> +
> +static inline int static int __zcache_init_kvm(void)
> +{
> +	return 0;
> +}
> +
> +#endif
> +
>  static int __init zcache_init(void)
>  {
>  	int ret = 0;
> @@ -2053,6 +2084,8 @@ static int __init zcache_init(void)
>  		pr_err("zcache: can't create client\n");
>  		goto out;
>  	}
> +	if (__zcache_init_kvm())
> +		goto out;
>  #endif
>  #ifdef CONFIG_CLEANCACHE
>  	if (zcache_enabled && use_cleancache) {
> -- 
> 1.7.8.6