Hi Henry,
+CC: Luca
On 17/05/2024 05:21, Henry Wang wrote:
>
>
> Currently, users are allowed to map static shared memory in a
> non-direct-mapped way for direct-mapped domains. This can lead to
> clashing of guest memory spaces. Also, the current extended region
> finding logic only removes the host physical addresses of the
> static shared memory areas for direct-mapped domains, which may be
> inconsistent with the guest memory map if users map the static
> shared memory in a non-direct-mapped way. This will lead to incorrect
> extended region calculation results.
>
> To make things easier, add restriction that static shared memory
> should also be direct-mapped for direct-mapped domains. Check the
> host physical address to be matched with guest physical address when
> parsing the device tree. Document this restriction in the doc.
I'm ok with this restriction.
@Luca, do you have any use case preventing us from making this restriction?
This patch clashes with Luca series so depending on which goes first,
Acked-by: Michal Orzel <michal.or...@amd.com>
>
> Signed-off-by: Henry Wang <xin.wa...@amd.com>
> ---
> v3:
> - New patch.
> ---
> docs/misc/arm/device-tree/booting.txt | 3 +++
> xen/arch/arm/static-shmem.c | 6 ++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/docs/misc/arm/device-tree/booting.txt
> b/docs/misc/arm/device-tree/booting.txt
> index bbd955e9c2..c994e48391 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -591,6 +591,9 @@ communication.
> shared memory region in host physical address space, a size, and a guest
> physical address, as the target address of the mapping.
> e.g. xen,shared-mem = < [host physical address] [guest address] [size] >
> + Note that if a domain is direct-mapped, i.e. the Dom0 and the Dom0less
> + DomUs with `direct-map` device tree property, the static shared memory
> + should also be direct-mapped (host physical address == guest address).
>
> It shall also meet the following criteria:
> 1) If the SHM ID matches with an existing region, the address range of
> the
> diff --git a/xen/arch/arm/static-shmem.c b/xen/arch/arm/static-shmem.c
> index 78881dd1d3..b26fb69874 100644
> --- a/xen/arch/arm/static-shmem.c
> +++ b/xen/arch/arm/static-shmem.c
> @@ -235,6 +235,12 @@ int __init process_shm(struct domain *d, struct
> kernel_info *kinfo,
> d, psize);
> return -EINVAL;
> }
> + if ( is_domain_direct_mapped(d) && (pbase != gbase) )
> + {
> + printk("%pd: physical address 0x%"PRIpaddr" and guest address
> 0x%"PRIpaddr" are not 1:1 direct-mapped.\n",
NIT: 1:1 and direct-mapped means the same so no need to place them next to each
other
> + d, pbase, gbase);
> + return -EINVAL;
> + }
>
> for ( i = 0; i < PFN_DOWN(psize); i++ )
> if ( !mfn_valid(mfn_add(maddr_to_mfn(pbase), i)) )
> --
> 2.34.1
>
>
~Michal
