On Thu, Jul 31, 2025 at 5:28 AM Petr Beneš <w1be...@gmail.com> wrote: > > From: Petr Beneš <w1be...@gmail.com> > > This commit introduces the ability to configure the maximum number of altp2m > views for the domain during its creation. Previously, the limits were > hardcoded > to a maximum of 10. This change allows for greater flexibility in environments > that require more or fewer altp2m views. > > The maximum configurable limit for nr_altp2m on x86 is now set to > MAX_NR_ALTP2M (which currently holds the MAX_EPTP value - 512). This cap is > linked to the architectural limit of the EPTP-switching VMFUNC, which supports > up to 512 entries. Despite there being no inherent need for limiting nr_altp2m > in scenarios not utilizing VMFUNC, decoupling these components would > necessitate > substantial code changes. > > xen_domctl_createdomain::altp2m is extended for a new field `nr`, that will > configure this limit for a domain. Additionally, previous altp2m.opts value > has been reduced from uint32_t to uint16_t so that both of these fields occupy > as little space as possible. > > Accesses to the altp2m_p2m array are modified to respect the new nr_altp2m > value. Accesses to the altp2m_(visible_)eptp arrays are unmodified, since > these arrays always have fixed size of MAX_EPTP. > > Additional sanitization is introduced in the x86/arch_sanitise_domain_config > to fix the altp2m.nr value to 10 if it is previously set to 0. This behavior > is only temporary and immediately removed in the upcoming commit (which will > disallow creating a domain with enabled altp2m with zero nr_altp2m). > > The reason for this temporary workaround is to retain the legacy behavior > until the feature is fully activated in libxl. > > Also, arm/arch_sanitise_domain_config is extended to not allow requesting > non-zero altp2ms. > > Signed-off-by: Petr Beneš <w1be...@gmail.com> > Acked-by: Jan Beulich <jbeul...@suse.com>
For mem_access/mem_sharing bits: Acked-by: Tamas K Lengyel <ta...@tklengyel.com>
