Date: Wed, 19 Dec 2012 12:09:03 +0000 (UTC) From: "Cherry G. Mathew" <cherry@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r244425 - projects/amd64_xen_pv/sys/amd64/xen Message-ID: <201212191209.qBJC93T4089069@svn.freebsd.org>
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Author: cherry Date: Wed Dec 19 12:09:02 2012 New Revision: 244425 URL: http://svnweb.freebsd.org/changeset/base/244425 Log: - Add a dummy userland pagetable pointer to keep xen happy. This allows us to hypervisor_iret() into xen to resume from exceptions. (Xen checks for a valid userland pagetable irrespective of the domain "mode" (ie; user/kernel)) being returned to. - Enhance xen_vm_vtop() to lookup early (boottime) kernel mappings. - A few more sanity checks ie; KASSERTS() Modified: projects/amd64_xen_pv/sys/amd64/xen/pmap.c Modified: projects/amd64_xen_pv/sys/amd64/xen/pmap.c ============================================================================== --- projects/amd64_xen_pv/sys/amd64/xen/pmap.c Wed Dec 19 12:00:09 2012 (r244424) +++ projects/amd64_xen_pv/sys/amd64/xen/pmap.c Wed Dec 19 12:09:02 2012 (r244425) @@ -429,7 +429,7 @@ pmap_xen_bootpages(vm_paddr_t *firstaddr uintptr_t va; vm_paddr_t ma; - /* Share info */ + /* i) Share info */ ma = xen_start_info->shared_info; /* This is a bit of a hack right now - we waste a physical @@ -452,6 +452,27 @@ pmap_xen_bootpages(vm_paddr_t *firstaddr PT_SET_MA(va, ma | PG_RW | PG_V | PG_U); HYPERVISOR_shared_info = (void *) va; + + + /* ii) Userland page table base */ + va = vallocpages(firstaddr, 1); + bzero((void *)va, PAGE_SIZE); + + /* + * x86_64 has 2 privilege rings and Xen keeps separate pml4 + * pointers for each, which are sanity checked on every + * exit via hypervisor_iret. We therefore set up a zeroed out + * user page table pml4 to satisfy/fool xen. + */ + + /* Mark the page r/o before pinning */ + pmap_xen_setpages_ro(va, 1); + + /* Pin the table */ + xen_pgdir_pin(phystomach(VTOP(va))); + + /* Register user page table with Xen */ + xen_pt_user_switch(VTOP(va)); } /* Boot time ptov - xen guarantees bootpages to be offset */ @@ -906,7 +927,12 @@ pmap_extract_and_hold(pmap_t pmap, vm_of vm_paddr_t pmap_kextract(vm_offset_t va) { - return xpmap_mtop(pmap_kextract_ma(va)); + vm_paddr_t ma; + ma = pmap_kextract_ma(va); + + KASSERT(ma != 0, ("%s: Unmapped va: 0x%lx \n", __func__, va)); + + return xpmap_mtop(ma); } vm_paddr_t @@ -1301,8 +1327,12 @@ xen_vm_vtop(uintptr_t va) { int result; - /* The kernel expects to have full access to its address space */ - const vm_prot_t accesstype = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE; + /* + * The kernel expects to have at least read access to its + * address space. On Xen we don't have full access, since + * page-table pages, for eg: are read-only. + */ + const vm_prot_t accesstype = VM_PROT_READ; vm_page_t m; vm_object_t object; /* Backing object for this va */ @@ -1315,12 +1345,20 @@ xen_vm_vtop(uintptr_t va) va <= VM_MAX_KERNEL_ADDRESS), ("Invalid kernel virtual address")); + if (va >= KERNBASE && va <= virtual_avail) { /* + * Boot time page + */ + return VTOP(va); + } + /* Get the specific object and pindex where the va may be mapped */ result = vm_map_lookup(&kernel_map, va, accesstype, &entry, &object, &pindex, &tmp_prot, &wired); - KASSERT(result == KERN_SUCCESS, ("Couldn't find va in the kernel map. \n")); - KASSERT(accesstype == tmp_prot, ("Kernel access permissions disparity\n")); + KASSERT(result == KERN_SUCCESS, ("Couldn't find va = 0x%lx in the kernel map. \n", va)); + + KASSERT(accesstype | tmp_prot, ("Kernel access permissions disparity for va = 0x%lx: %s\n", va, ((tmp_prot & VM_PROT_READ) ? "VM_PROT_READ" : ( + (tmp_prot & VM_PROT_WRITE) ? "| VM_PROT_WRITE" : ((tmp_prot & VM_PROT_EXECUTE) ? "| VM_PROT_EXECUTE" : ""))))); VM_OBJECT_LOCK(object);
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