Hi Stefano,
Wasn't this patch supposed to be folded with patch no.3 to avoid breaking the
bisection?
On 25/05/2024 00:55, Stefano Stabellini wrote:
> From: Henry Wang <xin.wa...@amd.com>
>
> There are use cases (for example using the PV driver) in Dom0less
> setup that require Dom0less DomUs start immediately with Dom0, but
> initialize XenStore later after Dom0's successful boot and call to
> the init-dom0less application.
>
> An error message can seen from the init-dom0less application on
> 1:1 direct-mapped domains:
> ```
> Allocating magic pages
> memory.c:238:d0v0 mfn 0x39000 doesn't belong to d1
> Error on alloc magic pages
> ```
>
> The "magic page" is a terminology used in the toolstack as reserved
> pages for the VM to have access to virtual platform capabilities.
> Currently the magic pages for Dom0less DomUs are populated by the
> init-dom0less app through populate_physmap(), and populate_physmap()
> automatically assumes gfn == mfn for 1:1 direct mapped domains. This
> cannot be true for the magic pages that are allocated later from the
> init-dom0less application executed in Dom0. For domain using statically
> allocated memory but not 1:1 direct-mapped, similar error "failed to
> retrieve a reserved page" can be seen as the reserved memory list is
> empty at that time.
>
> Since for init-dom0less, the magic page region is only for XenStore.
> To solve above issue, this commit allocates the XenStore page for
> Dom0less DomUs at the domain construction time. The PFN will be
> noted and communicated to the init-dom0less application executed
> from Dom0. To keep the XenStore late init protocol, set the connection
> status to XENSTORE_RECONNECT.
>
> Reported-by: Alec Kwapis <alec.kwa...@medtronic.com>
> Suggested-by: Daniel P. Smith <dpsm...@apertussolutions.com>
> Signed-off-by: Henry Wang <xin.wa...@amd.com>
> Signed-off-by: Stefano Stabellini <stefano.stabell...@amd.com>
> ---
> xen/arch/arm/dom0less-build.c | 55 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
> index 74f053c242..2963ecc0b3 100644
> --- a/xen/arch/arm/dom0less-build.c
> +++ b/xen/arch/arm/dom0less-build.c
> @@ -1,5 +1,6 @@
> /* SPDX-License-Identifier: GPL-2.0-only */
> #include <xen/device_tree.h>
> +#include <xen/domain_page.h>
> #include <xen/err.h>
> #include <xen/event.h>
> #include <xen/grant_table.h>
> @@ -10,6 +11,8 @@
> #include <xen/sizes.h>
> #include <xen/vmap.h>
>
> +#include <public/io/xs_wire.h>
> +
> #include <asm/arm64/sve.h>
> #include <asm/dom0less-build.h>
> #include <asm/domain_build.h>
> @@ -739,6 +742,53 @@ static int __init alloc_xenstore_evtchn(struct domain *d)
> return 0;
> }
>
> +#define XENSTORE_PFN_OFFSET 1
> +static int __init alloc_xenstore_page(struct domain *d)
> +{
> + struct page_info *xenstore_pg;
> + struct xenstore_domain_interface *interface;
> + mfn_t mfn;
> + gfn_t gfn;
> + int rc;
> +
> + if ( (UINT_MAX - d->max_pages) < 1 )
> + {
> + printk(XENLOG_ERR "%pd: Over-allocation for d->max_pages by 1
> page.\n",
> + d);
> + return -EINVAL;
> + }
> + d->max_pages += 1;
NIT: empty line here for readability
> + xenstore_pg = alloc_domheap_page(d, MEMF_bits(32));
> + if ( xenstore_pg == NULL && is_64bit_domain(d) )
> + xenstore_pg = alloc_domheap_page(d, 0);
> + if ( xenstore_pg == NULL )
> + return -ENOMEM;
> +
> + mfn = page_to_mfn(xenstore_pg);
> + if ( !mfn_x(mfn) )
> + return -ENOMEM;
I think you should free the allocated page here
Other than that:
Reviewed-by: Michal Orzel <michal.or...@amd.com>
~Michal
