On Wed, Dec 01, 2021 at 05:04:02PM +0000, Quentin Perret wrote: > In order to simplify the page tracking infrastructure at EL2 in nVHE > protected mode, move the responsibility of refcounting pages that are > shared multiple times on the host. In order to do so, let's create a > red-black tree tracking all the PFNs that have been shared, along with > a refcount. > > Signed-off-by: Quentin Perret <[email protected]> > --- > arch/arm64/kvm/mmu.c | 78 ++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 68 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index fd868fb9d922..d72566896755 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -284,23 +284,72 @@ static phys_addr_t kvm_kaddr_to_phys(void *kaddr) > } > } > > -static int pkvm_share_hyp(phys_addr_t start, phys_addr_t end) > +struct hyp_shared_pfn { > + u64 pfn; > + int count; > + struct rb_node node; > +}; > + > +static DEFINE_MUTEX(hyp_shared_pfns_lock); > +static struct rb_root hyp_shared_pfns = RB_ROOT; > + > +static struct hyp_shared_pfn *find_shared_pfn(u64 pfn, struct rb_node > ***node, > + struct rb_node **parent) > { > - phys_addr_t addr; > - int ret; > + struct hyp_shared_pfn *this; > + > + *node = &hyp_shared_pfns.rb_node; > + *parent = NULL; > + while (**node) { > + this = container_of(**node, struct hyp_shared_pfn, node); > + *parent = **node; > + if (this->pfn < pfn) > + *node = &((**node)->rb_left); > + else if (this->pfn > pfn) > + *node = &((**node)->rb_right); > + else > + return this; > + } > > - for (addr = ALIGN_DOWN(start, PAGE_SIZE); addr < end; addr += > PAGE_SIZE) { > - ret = kvm_call_hyp_nvhe(__pkvm_host_share_hyp, > - __phys_to_pfn(addr)); > - if (ret) > - return ret; > + return NULL; > +} > + > +static int share_pfn_hyp(u64 pfn) > +{ > + struct rb_node **node, *parent; > + struct hyp_shared_pfn *this; > + int ret = 0; > + > + mutex_lock(&hyp_shared_pfns_lock); > + this = find_shared_pfn(pfn, &node, &parent);
I don't think this is a fast-path at the moment, but in the future we might consider using RCU to do the lookup outside of the mutex. But as-is: Acked-by: Will Deacon <[email protected]> Will _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
