From: Stefano Stabellini <sstabellini@kernel.org>
To: Oleksandr <olekstysh@gmail.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
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>,
Juergen Gross <jgross@suse.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: Mon, 18 Apr 2022 12:11:16 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2204181156280.915916@ubuntu-linux-20-04-desktop> (raw)
In-Reply-To: <84f5264c-6b98-6d56-b7ca-61c19dc502ca@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 4444 bytes --]
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.
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next prev parent reply other threads:[~2022-04-18 19:12 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 [this message]
2022-04-19 6:58 ` Juergen Gross
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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