Date: Wed, 19 Dec 2012 17:40:01 +0530 From: Cherry G. Mathew <cherry@zyx.in> To: src-committers@freebsd.org Cc: svn-src-projects@freebsd.org Subject: Re: svn commit: r244425 - projects/amd64_xen_pv/sys/amd64/xen Message-ID: <878v8uckfa.fsf@zyx.in> In-Reply-To: <201212191209.qBJC93T4089069@svn.freebsd.org> (Cherry G. Mathew's message of "Wed, 19 Dec 2012 12:09:03 %2B0000 (UTC)") References: <201212191209.qBJC93T4089069@svn.freebsd.org>
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Apologies for deviating from the checkin log template.
Approved by: gibbs(implicit)
>>>>> "Cherry" == Cherry G Mathew <cherry@FreeBSD.org> writes:
Cherry> Author: cherry Date: Wed Dec 19 12:09:02 2012 New Revision:
Cherry> 244425 URL: http://svnweb.freebsd.org/changeset/base/244425
Cherry> Log: - Add a dummy userland pagetable pointer to keep xen
Cherry> happy. This allows us to hypervisor_iret() into xen to
Cherry> resume from exceptions. (Xen checks for a valid userland
Cherry> pagetable irrespective of the domain "mode" (ie;
Cherry> user/kernel)) being returned to. - Enhance xen_vm_vtop() to
Cherry> lookup early (boottime) kernel mappings. - A few more
Cherry> sanity checks ie; KASSERTS()
Cherry> Modified: projects/amd64_xen_pv/sys/amd64/xen/pmap.c
Cherry> Modified: projects/amd64_xen_pv/sys/amd64/xen/pmap.c
Cherry> ==============================================================================
Cherry> --- projects/amd64_xen_pv/sys/amd64/xen/pmap.c Wed Dec 19
Cherry> 12:00:09 2012 (r244424) +++
Cherry> projects/amd64_xen_pv/sys/amd64/xen/pmap.c Wed Dec 19
Cherry> 12:09:02 2012 (r244425) @@ -429,7 +429,7 @@
Cherry> pmap_xen_bootpages(vm_paddr_t *firstaddr uintptr_t va;
Cherry> vm_paddr_t ma;
Cherry> - /* Share info */ + /* i) Share info */ ma =
Cherry> xen_start_info->shared_info;
Cherry> /* This is a bit of a hack right now - we waste a
Cherry> physical @@ -452,6 +452,27 @@ pmap_xen_bootpages(vm_paddr_t
Cherry> *firstaddr PT_SET_MA(va, ma | PG_RW | PG_V | PG_U);
Cherry> HYPERVISOR_shared_info = (void *) va; + + + /* ii)
Cherry> Userland page table base */ + va = vallocpages(firstaddr,
Cherry> 1); + bzero((void *)va, PAGE_SIZE); + + /* + * x86_64 has 2
Cherry> privilege rings and Xen keeps separate pml4 + * pointers for
Cherry> each, which are sanity checked on every + * exit via
Cherry> hypervisor_iret. We therefore set up a zeroed out + * user
Cherry> page table pml4 to satisfy/fool xen. + */ + + /* Mark the
Cherry> page r/o before pinning */ + pmap_xen_setpages_ro(va, 1); +
Cherry> + /* Pin the table */ + xen_pgdir_pin(phystomach(VTOP(va)));
Cherry> + + /* Register user page table with Xen */ +
Cherry> xen_pt_user_switch(VTOP(va));
Cherry> }
Cherry> /* Boot time ptov - xen guarantees bootpages to be offset
Cherry> */ @@ -906,7 +927,12 @@ pmap_extract_and_hold(pmap_t pmap,
Cherry> vm_of vm_paddr_t pmap_kextract(vm_offset_t va) { - return
Cherry> xpmap_mtop(pmap_kextract_ma(va)); + vm_paddr_t ma; + ma =
Cherry> pmap_kextract_ma(va); + + KASSERT(ma != 0, ("%s: Unmapped
Cherry> va: 0x%lx \n", __func__, va)); + + return xpmap_mtop(ma);
Cherry> }
Cherry> vm_paddr_t @@ -1301,8 +1327,12 @@ xen_vm_vtop(uintptr_t va)
Cherry> { int result;
Cherry> - /* The kernel expects to have full access to its address
Cherry> space */ - const vm_prot_t accesstype = VM_PROT_READ |
Cherry> VM_PROT_WRITE | VM_PROT_EXECUTE; + /* + * The kernel expects
Cherry> to have at least read access to its + * address space. On
Cherry> Xen we don't have full access, since + * page-table pages,
Cherry> for eg: are read-only. + */ + const vm_prot_t accesstype =
Cherry> VM_PROT_READ;
Cherry> vm_page_t m; vm_object_t object; /* Backing object for
Cherry> this va */ @@ -1315,12 +1345,20 @@ xen_vm_vtop(uintptr_t va)
Cherry> va <= VM_MAX_KERNEL_ADDRESS), ("Invalid kernel virtual
Cherry> address"));
Cherry> + if (va >= KERNBASE && va <= virtual_avail) { /* + * Boot
Cherry> time page + */ + return VTOP(va); + } + /* Get the specific
Cherry> object and pindex where the va may be mapped */ result =
Cherry> vm_map_lookup(&kernel_map, va, accesstype, &entry, &object,
Cherry> &pindex, &tmp_prot, &wired);
Cherry> - KASSERT(result == KERN_SUCCESS, ("Couldn't find va in the
Cherry> kernel map. \n")); - KASSERT(accesstype == tmp_prot,
Cherry> ("Kernel access permissions disparity\n")); + KASSERT(result
Cherry> == KERN_SUCCESS, ("Couldn't find va = 0x%lx in the kernel
Cherry> map. \n", va)); + + KASSERT(accesstype | tmp_prot, ("Kernel
Cherry> access permissions disparity for va = 0x%lx: %s\n", va,
Cherry> ((tmp_prot & VM_PROT_READ) ? "VM_PROT_READ" : ( + (tmp_prot
Cherry> & VM_PROT_WRITE) ? "| VM_PROT_WRITE" : ((tmp_prot &
Cherry> VM_PROT_EXECUTE) ? "| VM_PROT_EXECUTE" : "")))));
Cherry> VM_OBJECT_LOCK(object);
--
Cherry
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