From: Jan Beulich <jbeulich@suse.com>
To: Penny Zheng <Penny.Zheng@arm.com>
Cc: wei.chen@arm.com, Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>, Wei Liu <wl@xen.org>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 2/9] xen/arm: allocate static shared memory to the default owner dom_io
Date: Fri, 6 May 2022 12:13:05 +0200 [thread overview]
Message-ID: <387bcb63-f9a7-0032-bcd5-088b65b9c10d@suse.com> (raw)
In-Reply-To: <20220506072502.2177828-3-Penny.Zheng@arm.com>
On 06.05.2022 09:24, Penny Zheng wrote:
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -777,8 +777,22 @@ void __init setup_system_domains(void)
>
> /*
> * Initialise our DOMID_IO domain.
> - * This domain owns I/O pages that are within the range of the page_info
> - * array. Mappings occur at the priv of the caller.
This information is effectively lost; I cannot spot a suitable replacement
in the new text.
> + * DOMID_IO is used for mapping memory and MMIO regions when no explicit
> + * Domain need to be specified.
> + *
> + * For instance, DOMID_IO is the owner of memory pre-shared among
> + * multiple domains at boot time, when no explicit owner is specified.
> + *
> + * Also, DOMID_IO is used to restrict page-table updates to mapping I/O
> + * memory. Although no Foreign Domain need to be specified to map I/O
> + * pages, DOMID_IO is useful to ensure that no mappings to the OS's own
> + * heap are accidentally installed. (e.g., in Linux this could cause
> + * havoc as reference counts aren't adjusted on the I/O-mapping code
> + * path). This only makes sense as HYPERVISOR_mmu_update()'s and
> + * HYPERVISOR_update_va_mapping_otherdomain()'s "foreigndom" argument.
> + * For HYPERVISOR_mmu_update() context it can be specified by any
> + * calling domain, otherwise it's only permitted if the caller is
> + * privileged.
Much of this looks to have been copied from the public header. I don't
see why you did this; if anything a reference there would suffice.
> * Quarantined PCI devices will be associated with this domain.
> */
I would also like to ask that you add the new purpose of this domain
_below_ all pre-existing ones, such that this also somewhat expressed
how things have evolved.
Jan
next prev parent reply other threads:[~2022-05-06 10:13 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 7:24 [PATCH v2 0/9] static shared memory on dom0less system Penny Zheng
2022-05-06 7:24 ` [PATCH v2 1/9] xen/arm: introduce static shared memory Penny Zheng
2022-05-07 1:08 ` Stefano Stabellini
2022-05-07 6:43 ` Penny Zheng
2022-05-06 7:24 ` [PATCH v2 2/9] xen/arm: allocate static shared memory to the default owner dom_io Penny Zheng
2022-05-06 10:13 ` Jan Beulich [this message]
2022-05-07 1:08 ` Stefano Stabellini
2022-05-06 7:24 ` [PATCH v2 3/9] xen/arm: allocate static shared memory to a specific owner domain Penny Zheng
2022-05-07 1:08 ` Stefano Stabellini
2022-05-06 7:24 ` [PATCH v2 4/9] xen/arm: introduce put_page_nr and get_page_nr Penny Zheng
2022-05-07 1:08 ` Stefano Stabellini
2022-05-07 8:04 ` Penny Zheng
2022-05-09 19:10 ` Stefano Stabellini
2022-05-07 9:10 ` Julien Grall
2022-05-06 7:24 ` [PATCH v2 5/9] xen/arm: Add additional reference to owner domain when the owner is allocated Penny Zheng
2022-05-07 1:09 ` Stefano Stabellini
2022-05-06 7:24 ` [PATCH v2 6/9] xen/arm: add P2M type parameter in guest_physmap_add_pages Penny Zheng
2022-05-07 1:09 ` Stefano Stabellini
2022-05-07 9:00 ` Julien Grall
2022-05-07 9:20 ` Penny Zheng
2022-05-06 7:25 ` [PATCH v2 7/9] xen/arm: set up shared memory foreign mapping for borrower domain Penny Zheng
2022-05-07 1:09 ` Stefano Stabellini
2022-05-06 7:25 ` [PATCH v2 8/9] xen/arm: create shared memory nodes in guest device tree Penny Zheng
2022-05-07 1:09 ` Stefano Stabellini
2022-05-07 11:26 ` Julien Grall
2022-05-06 7:25 ` [PATCH v2 9/9] xen/arm: enable statically shared memory on Dom0 Penny Zheng
2022-05-07 1:09 ` Stefano Stabellini
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