From: Juergen Gross <jgross@suse.com>
To: Stefano Stabellini <sstabellini@kernel.org>,
Oleksandr <olekstysh@gmail.com>
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
Russell King <linux@armlinux.org.uk>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Julien Grall <julien@xen.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC PATCH 4/6] virtio: Various updates to xen-virtio DMA ops layer
Date: Tue, 19 Apr 2022 08:58:20 +0200 [thread overview]
Message-ID: <de61ab3a-a6e9-0209-f06a-dc04d3b14f5d@suse.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2204181156280.915916@ubuntu-linux-20-04-desktop>
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On 18.04.22 21:11, Stefano Stabellini wrote:
> On Sun, 17 Apr 2022, Oleksandr wrote:
>> On 16.04.22 01:02, Stefano Stabellini wrote:
>>> On Thu, 14 Apr 2022, Oleksandr Tyshchenko wrote:
>>>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>>>
>>>> In the context of current patch do the following:
>>>> 1. Update code to support virtio-mmio devices
>>>> 2. Introduce struct xen_virtio_data and account passed virtio devices
>>>> (using list) as we need to store some per-device data
>>>> 3. Add multi-page support for xen_virtio_dma_map(unmap)_page callbacks
>>>> 4. Harden code against malicious backend
>>>> 5. Change to use alloc_pages_exact() instead of __get_free_pages()
>>>> 6. Introduce locking scheme to protect mappings (I am not 100% sure
>>>> whether per-device lock is really needed)
>>>> 7. Handle virtio device's DMA mask
>>>> 8. Retrieve the ID of backend domain from DT for virtio-mmio device
>>>> instead of hardcoding it.
>>>>
>>>> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>>> ---
>>>> arch/arm/xen/enlighten.c | 11 +++
>>>> drivers/xen/Kconfig | 2 +-
>>>> drivers/xen/xen-virtio.c | 200
>>>> ++++++++++++++++++++++++++++++++++++++++++-----
>>>> include/xen/xen-ops.h | 5 ++
>>>> 4 files changed, 196 insertions(+), 22 deletions(-)
>>>>
>>>> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
>>>> index ec5b082..870d92f 100644
>>>> --- a/arch/arm/xen/enlighten.c
>>>> +++ b/arch/arm/xen/enlighten.c
>>>> @@ -409,6 +409,17 @@ int __init arch_xen_unpopulated_init(struct resource
>>>> **res)
>>>> }
>>>> #endif
>>>> +#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
>>>> +int arch_has_restricted_virtio_memory_access(void)
>>>> +{
>>>> + if (IS_ENABLED(CONFIG_XEN_HVM_VIRTIO_GRANT) && xen_hvm_domain())
>>>> + return 1;
>>> Instead of xen_hvm_domain(), you can just use xen_domain(). Also there
>>> is no need for the #ifdef
>>> CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, given that:
>>>
>>> CONFIG_XEN_HVM_VIRTIO_GRANT depends on XEN_VIRTIO which selects
>>> ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
>>
>>
>> Yes, but please see my comments in commit #2 regarding
>> CONFIG_XEN_HVM_VIRTIO_GRANT option and
>> arch_has_restricted_virtio_memory_access() on Arm.
>>
>> I propose to have the following on Arm:
>>
>> int arch_has_restricted_virtio_memory_access(void)
>> {
>> return xen_has_restricted_virtio_memory_access();
>> }
>>
>>
>> where common xen.h contain a helper to be used by both Arm and x86:
>>
>> static inline int xen_has_restricted_virtio_memory_access(void)
>> {
>> if (IS_ENABLED(CONFIG_XEN_VIRTIO) && (xen_pv_domain() ||
>> xen_hvm_domain()))
>> return 1;
>>
>> return 0;
>> }
>>
>>
>> But I would be happy with what you propose as well.
>
> As I wrote in the previous reply, I also prefer to share the code
> between x86 and ARM, and I think it could look like:
>
> int arch_has_restricted_virtio_memory_access(void)
> {
> return xen_has_restricted_virtio_memory_access();
> }
> [...]
> static inline int xen_has_restricted_virtio_memory_access(void)
> {
> return (IS_ENABLED(CONFIG_XEN_VIRTIO) && xen_domain());
> }
>
> But let's check with Juergen and Boris.
>
>
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(arch_has_restricted_virtio_memory_access);
>>>> +#endif
>>>> +
>>>> static void __init xen_dt_guest_init(void)
>>>> {
>>>> struct device_node *xen_node;
>>>> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
>>>> index fc61f7a..56afe6a 100644
>>>> --- a/drivers/xen/Kconfig
>>>> +++ b/drivers/xen/Kconfig
>>>> @@ -347,7 +347,7 @@ config XEN_VIRTIO
>>>> config XEN_HVM_VIRTIO_GRANT
>>>> bool "Require virtio for fully virtualized guests to use grant
>>>> mappings"
>>>> - depends on XEN_VIRTIO && X86_64
>>>> + depends on XEN_VIRTIO && (X86_64 || ARM || ARM64)
>>> you can remove the architectural dependencies
>>
>>
>> According to the conversation in commit #2 we are considering just a single
>> XEN_VIRTIO option, but it is going to has the
>> same architectural dependencies: (X86_64 || ARM || ARM64)
>>
>> By removing the architectural dependencies here, we will leave also X86_32
>> covered (neither XEN_HVM_VIRTIO_GRANT nor XEN_PV_VIRTIO covered it). I don't
>> know whether it is ok or not.
>>
>> Shall I remove dependencies anyway?
>
> No, good point. I don't know about X86_32. This is another detail where
> Juergen or Boris should comment.
X86_32 should in theory work (it is HVM/PVH only, as PV 32-bit guests are no
longer supported).
Juergen
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next prev parent reply other threads:[~2022-04-19 7:29 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-14 19:19 [RFC PATCH 0/6] virtio: Solution to restrict memory access under Xen using xen-virtio DMA ops layer Oleksandr Tyshchenko
2022-04-14 19:19 ` [RFC PATCH 1/6] xen/grants: support allocating consecutive grants Oleksandr Tyshchenko
2022-04-14 19:19 ` [RFC PATCH 2/6] virtio: add option to restrict memory access under Xen Oleksandr Tyshchenko
[not found] ` <5A795507-715D-494B-B56B-B12E5BE348A4@zytor.com>
2022-04-15 15:20 ` Oleksandr
[not found] ` <alpine.DEB.2.22.394.2204151235440.915916@ubuntu-linux-20-04-desktop>
2022-04-17 17:02 ` Oleksandr
2022-04-18 19:11 ` Stefano Stabellini
2022-04-19 6:21 ` Juergen Gross
2022-04-19 6:37 ` Oleksandr
2022-04-14 19:19 ` [RFC PATCH 3/6] dt-bindings: xen: Add xen, dev-domid property description for xen-virtio layer Oleksandr Tyshchenko
[not found] ` <alpine.DEB.2.22.394.2204151300130.915916@ubuntu-linux-20-04-desktop>
2022-04-17 17:24 ` [RFC PATCH 3/6] dt-bindings: xen: Add xen,dev-domid " Oleksandr
2022-04-14 19:19 ` [RFC PATCH 4/6] virtio: Various updates to xen-virtio DMA ops layer Oleksandr Tyshchenko
2022-04-15 22:02 ` Stefano Stabellini
2022-04-17 18:21 ` Oleksandr
2022-04-18 19:11 ` Stefano Stabellini
2022-04-19 6:58 ` Juergen Gross [this message]
2022-04-19 7:07 ` Oleksandr
2022-04-16 6:05 ` Christoph Hellwig
2022-04-17 18:39 ` Oleksandr
2022-04-14 19:19 ` [RFC PATCH 5/6] arm/xen: Introduce xen_setup_dma_ops() Oleksandr Tyshchenko
2022-04-15 22:02 ` Stefano Stabellini
2022-04-17 18:43 ` Oleksandr
2022-04-14 19:19 ` [RFC PATCH 6/6] arm/xen: Assign xen-virtio DMA ops for virtio devices in Xen guests Oleksandr Tyshchenko
2022-04-15 22:02 ` Stefano Stabellini
2022-04-16 6:07 ` Christoph Hellwig
2022-04-17 21:05 ` Oleksandr
2022-04-18 19:11 ` Stefano Stabellini
2022-04-19 12:17 ` Oleksandr
2022-04-19 14:48 ` Juergen Gross
2022-04-19 17:11 ` Oleksandr
2022-04-20 0:23 ` Stefano Stabellini
2022-04-20 9:00 ` Oleksandr
2022-04-20 22:49 ` Stefano Stabellini
2022-04-17 19:20 ` Oleksandr
2022-04-15 7:41 ` [RFC PATCH 0/6] virtio: Solution to restrict memory access under Xen using xen-virtio DMA ops layer Christoph Hellwig
2022-04-15 10:04 ` Oleksandr
2022-04-15 8:44 ` Michael S. Tsirkin
2022-04-15 15:29 ` Oleksandr
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