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Message-ID: <f62a1e2c-4253-c998-c206-6bb0681a84fb@epam.com>
Date: Fri, 24 Sep 2021 05:46:17 +0000
From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@...m.com>
To: Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Andrushchenko <andr2000@...il.com>
CC: "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
"jgross@...e.com" <jgross@...e.com>,
"julien@....org" <julien@....org>,
"jbeulich@...e.com" <jbeulich@...e.com>,
Anastasiia Lukianenko <Anastasiia_Lukianenko@...m.com>
Subject: Re: [PATCH v3 2/2] xen-pciback: allow compiling on other archs than
x86
On 23.09.21 23:00, Stefano Stabellini wrote:
> On Thu, 23 Sep 2021, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>
>> Xen-pciback driver was designed to be built for x86 only. But it
>> can also be used by other architectures, e.g. Arm.
>> Re-structure the driver in a way that it can be built for other
>> platforms as well.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>> Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@...m.com>
> The patch looks good to me. Only one thing: on ARM32 I get:
WE do not yet support Xen PCI passthrough for ARM32
>
> drivers/xen/xen-pciback/conf_space_header.c: In function ‘bar_init’:
> drivers/xen/xen-pciback/conf_space_header.c:239:34: warning: right shift count >= width of type [-Wshift-count-overflow]
> bar->val = res[pos - 1].start >> 32;
> ^~
> drivers/xen/xen-pciback/conf_space_header.c:240:49: warning: right shift count >= width of type [-Wshift-count-overflow]
> bar->len_val = -resource_size(&res[pos - 1]) >> 32;
>
>
> resource_size_t is defined as phys_addr_t and it can be 32bit on arm32.
>
>
> One fix is to surround:
>
> if (pos && (res[pos - 1].flags & IORESOURCE_MEM_64)) {
> bar->val = res[pos - 1].start >> 32;
> bar->len_val = -resource_size(&res[pos - 1]) >> 32;
> return bar;
> }
>
> with #ifdef PHYS_ADDR_T_64BIT
>
This might not be correct. We are dealing here with a 64-bit BAR on a 32-bit OS.
I think that this can still be valid use-case if BAR64.hi == 0. So, not sure
we can just skip it with ifdef.
Instead, to be on the safe side, we can have:
config XEN_PCIDEV_STUB
tristate "Xen PCI-device stub driver"
depends on PCI && ARM64 && XEN
e.g. only allow building the "stub" for ARM64 for now.
>
>> ---
>> Since v2:
>> - swap the patch order
>> Since v1:
>> - Do not move pci_xen_initial_domain as it is x86 specific
>> ---
>> arch/x86/include/asm/xen/pci.h | 18 +------
>> arch/x86/pci/xen.c | 74 +----------------------------
>> drivers/xen/pci.c | 75 ++++++++++++++++++++++++++++++
>> drivers/xen/xen-pciback/pci_stub.c | 3 +-
>> drivers/xen/xen-pciback/xenbus.c | 2 +-
>> include/xen/pci.h | 28 +++++++++++
>> 6 files changed, 108 insertions(+), 92 deletions(-)
>> create mode 100644 include/xen/pci.h
>>
>> diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
>> index 3506d8c598c1..2889f091f459 100644
>> --- a/arch/x86/include/asm/xen/pci.h
>> +++ b/arch/x86/include/asm/xen/pci.h
>> @@ -16,26 +16,10 @@ static inline int pci_xen_hvm_init(void)
>> #endif
>> #if defined(CONFIG_XEN_DOM0)
>> int __init pci_xen_initial_domain(void);
>> -int xen_find_device_domain_owner(struct pci_dev *dev);
>> -int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
>> -int xen_unregister_device_domain_owner(struct pci_dev *dev);
>> #else
>> static inline int __init pci_xen_initial_domain(void)
>> {
>> - return -1;
>> -}
>> -static inline int xen_find_device_domain_owner(struct pci_dev *dev)
>> -{
>> - return -1;
>> -}
>> -static inline int xen_register_device_domain_owner(struct pci_dev *dev,
>> - uint16_t domain)
>> -{
>> - return -1;
>> -}
>> -static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
>> -{
>> - return -1;
>> + return -1;
>> }
>> #endif
>>
>> diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
>> index 3d41a09c2c14..4a45b0bf9ae4 100644
>> --- a/arch/x86/pci/xen.c
>> +++ b/arch/x86/pci/xen.c
>> @@ -23,6 +23,7 @@
>>
>> #include <xen/features.h>
>> #include <xen/events.h>
>> +#include <xen/pci.h>
>> #include <asm/xen/pci.h>
>> #include <asm/xen/cpuid.h>
>> #include <asm/apic.h>
>> @@ -583,77 +584,4 @@ int __init pci_xen_initial_domain(void)
>> }
>> return 0;
>> }
>> -
>> -struct xen_device_domain_owner {
>> - domid_t domain;
>> - struct pci_dev *dev;
>> - struct list_head list;
>> -};
>> -
>> -static DEFINE_SPINLOCK(dev_domain_list_spinlock);
>> -static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
>> -
>> -static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
>> -{
>> - struct xen_device_domain_owner *owner;
>> -
>> - list_for_each_entry(owner, &dev_domain_list, list) {
>> - if (owner->dev == dev)
>> - return owner;
>> - }
>> - return NULL;
>> -}
>> -
>> -int xen_find_device_domain_owner(struct pci_dev *dev)
>> -{
>> - struct xen_device_domain_owner *owner;
>> - int domain = -ENODEV;
>> -
>> - spin_lock(&dev_domain_list_spinlock);
>> - owner = find_device(dev);
>> - if (owner)
>> - domain = owner->domain;
>> - spin_unlock(&dev_domain_list_spinlock);
>> - return domain;
>> -}
>> -EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
>> -
>> -int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
>> -{
>> - struct xen_device_domain_owner *owner;
>> -
>> - owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
>> - if (!owner)
>> - return -ENODEV;
>> -
>> - spin_lock(&dev_domain_list_spinlock);
>> - if (find_device(dev)) {
>> - spin_unlock(&dev_domain_list_spinlock);
>> - kfree(owner);
>> - return -EEXIST;
>> - }
>> - owner->domain = domain;
>> - owner->dev = dev;
>> - list_add_tail(&owner->list, &dev_domain_list);
>> - spin_unlock(&dev_domain_list_spinlock);
>> - return 0;
>> -}
>> -EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
>> -
>> -int xen_unregister_device_domain_owner(struct pci_dev *dev)
>> -{
>> - struct xen_device_domain_owner *owner;
>> -
>> - spin_lock(&dev_domain_list_spinlock);
>> - owner = find_device(dev);
>> - if (!owner) {
>> - spin_unlock(&dev_domain_list_spinlock);
>> - return -ENODEV;
>> - }
>> - list_del(&owner->list);
>> - spin_unlock(&dev_domain_list_spinlock);
>> - kfree(owner);
>> - return 0;
>> -}
>> -EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
>> #endif
>> diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
>> index 224df03ce42e..fc8c1249d49f 100644
>> --- a/drivers/xen/pci.c
>> +++ b/drivers/xen/pci.c
>> @@ -254,3 +254,78 @@ static int xen_mcfg_late(void)
>> return 0;
>> }
>> #endif
>> +
>> +#ifdef CONFIG_XEN_DOM0
>> +struct xen_device_domain_owner {
>> + domid_t domain;
>> + struct pci_dev *dev;
>> + struct list_head list;
>> +};
>> +
>> +static DEFINE_SPINLOCK(dev_domain_list_spinlock);
>> +static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
>> +
>> +static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
>> +{
>> + struct xen_device_domain_owner *owner;
>> +
>> + list_for_each_entry(owner, &dev_domain_list, list) {
>> + if (owner->dev == dev)
>> + return owner;
>> + }
>> + return NULL;
>> +}
>> +
>> +int xen_find_device_domain_owner(struct pci_dev *dev)
>> +{
>> + struct xen_device_domain_owner *owner;
>> + int domain = -ENODEV;
>> +
>> + spin_lock(&dev_domain_list_spinlock);
>> + owner = find_device(dev);
>> + if (owner)
>> + domain = owner->domain;
>> + spin_unlock(&dev_domain_list_spinlock);
>> + return domain;
>> +}
>> +EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
>> +
>> +int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
>> +{
>> + struct xen_device_domain_owner *owner;
>> +
>> + owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
>> + if (!owner)
>> + return -ENODEV;
>> +
>> + spin_lock(&dev_domain_list_spinlock);
>> + if (find_device(dev)) {
>> + spin_unlock(&dev_domain_list_spinlock);
>> + kfree(owner);
>> + return -EEXIST;
>> + }
>> + owner->domain = domain;
>> + owner->dev = dev;
>> + list_add_tail(&owner->list, &dev_domain_list);
>> + spin_unlock(&dev_domain_list_spinlock);
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
>> +
>> +int xen_unregister_device_domain_owner(struct pci_dev *dev)
>> +{
>> + struct xen_device_domain_owner *owner;
>> +
>> + spin_lock(&dev_domain_list_spinlock);
>> + owner = find_device(dev);
>> + if (!owner) {
>> + spin_unlock(&dev_domain_list_spinlock);
>> + return -ENODEV;
>> + }
>> + list_del(&owner->list);
>> + spin_unlock(&dev_domain_list_spinlock);
>> + kfree(owner);
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
>> +#endif
>> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
>> index f8e4faa96ad6..bba527620507 100644
>> --- a/drivers/xen/xen-pciback/pci_stub.c
>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>> @@ -19,7 +19,8 @@
>> #include <linux/sched.h>
>> #include <linux/atomic.h>
>> #include <xen/events.h>
>> -#include <asm/xen/pci.h>
>> +#include <xen/pci.h>
>> +#include <xen/xen.h>
>> #include <asm/xen/hypervisor.h>
>> #include <xen/interface/physdev.h>
>> #include "pciback.h"
>> diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
>> index f8ba2903a3ff..bde63ef677b8 100644
>> --- a/drivers/xen/xen-pciback/xenbus.c
>> +++ b/drivers/xen/xen-pciback/xenbus.c
>> @@ -14,7 +14,7 @@
>> #include <linux/workqueue.h>
>> #include <xen/xenbus.h>
>> #include <xen/events.h>
>> -#include <asm/xen/pci.h>
>> +#include <xen/pci.h>
>> #include "pciback.h"
>>
>> #define INVALID_EVTCHN_IRQ (-1)
>> diff --git a/include/xen/pci.h b/include/xen/pci.h
>> new file mode 100644
>> index 000000000000..b8337cf85fd1
>> --- /dev/null
>> +++ b/include/xen/pci.h
>> @@ -0,0 +1,28 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +#ifndef __XEN_PCI_H__
>> +#define __XEN_PCI_H__
>> +
>> +#if defined(CONFIG_XEN_DOM0)
>> +int xen_find_device_domain_owner(struct pci_dev *dev);
>> +int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
>> +int xen_unregister_device_domain_owner(struct pci_dev *dev);
>> +#else
>> +static inline int xen_find_device_domain_owner(struct pci_dev *dev)
>> +{
>> + return -1;
>> +}
>> +
>> +static inline int xen_register_device_domain_owner(struct pci_dev *dev,
>> + uint16_t domain)
>> +{
>> + return -1;
>> +}
>> +
>> +static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
>> +{
>> + return -1;
>> +}
>> +#endif
>> +
>> +#endif
>> --
>> 2.25.1
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