tools/libs/ctrl: fix xc_core_arch_map_p2m() to support linear p2m table

The core of a pv linux guest produced via "xl dump-core" is not usable
as since kernel 4.14 only the linear p2m table is kept if Xen indicates
it is supporting that. Unfortunately xc_core_arch_map_p2m() is still
supporting the 3-level p2m tree only.

Fix that by copying the functionality of map_p2m() from libxenguest to
libxenctrl.

Additionally the mapped p2m isn't of a fixed length now, so the
interface to the mapping functions needs to be adapted. In order not to
add even more parameters, expand struct domain_info_context and use a
pointer to that as a parameter.

This is a backport of upstream commit bd7a29c3d0.

As the original patch includes a modification of a data structure
passed via pointer to a library function, the related function in the
library is renamed in order to be able to spot any external users of
that function. Note that it is extremely unlikely any such users
outside the Xen git tree are existing, so the risk to break any
existing programs is very unlikely. In case such a user is existing,
changing the name of xc_map_domain_meminfo() will at least avoid
silent breakage.

Fixes: dc6d609371 ("libxc: set flag for support of linear p2m list in domain builder")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Ian Jackson <iwj@xenproject.org>

tools/include/xenguest.h

@@ -700,8 +700,10 @@ struct xc_domain_meminfo {
     xen_pfn_t *pfn_type;
     xen_pfn_t *p2m_table;
     unsigned long p2m_size;
+    unsigned int p2m_frames;
 };
 
+#define xc_map_domain_meminfo xc_map_domain_meminfo_mod
 int xc_map_domain_meminfo(xc_interface *xch, uint32_t domid,
                           struct xc_domain_meminfo *minfo);
 

tools/libs/ctrl/xc_core.c

@@ -574,8 +574,7 @@ xc_domain_dumpcore_via_callback(xc_interface *xch,
             goto out;
         }
 
-        sts = xc_core_arch_map_p2m(xch, dinfo->guest_width, &info, live_shinfo,
-                                   &p2m, &dinfo->p2m_size);
+        sts = xc_core_arch_map_p2m(xch, dinfo, &info, live_shinfo, &p2m);
         if ( sts != 0 )
             goto out;
 
@@ -945,7 +944,7 @@ out:
     if ( memory_map != NULL )
         free(memory_map);
     if ( p2m != NULL )
-        munmap(p2m, PAGE_SIZE * P2M_FL_ENTRIES);
+        munmap(p2m, PAGE_SIZE * dinfo->p2m_frames);
     if ( p2m_array != NULL )
         free(p2m_array);
     if ( pfn_array != NULL )

tools/libs/ctrl/xc_core.h

@@ -138,14 +138,14 @@ int xc_core_arch_memory_map_get(xc_interface *xch,
                                 xc_dominfo_t *info, shared_info_any_t *live_shinfo,
                                 xc_core_memory_map_t **mapp,
                                 unsigned int *nr_entries);
-int xc_core_arch_map_p2m(xc_interface *xch, unsigned int guest_width,
+int xc_core_arch_map_p2m(xc_interface *xch, struct domain_info_context *dinfo,
                          xc_dominfo_t *info, shared_info_any_t *live_shinfo,
-                         xen_pfn_t **live_p2m, unsigned long *pfnp);
+                         xen_pfn_t **live_p2m);
 
-int xc_core_arch_map_p2m_writable(xc_interface *xch, unsigned int guest_width,
+int xc_core_arch_map_p2m_writable(xc_interface *xch, struct domain_info_context *dinfo,
                                   xc_dominfo_t *info,
                                   shared_info_any_t *live_shinfo,
-                                  xen_pfn_t **live_p2m, unsigned long *pfnp);
+                                  xen_pfn_t **live_p2m);
 
 int xc_core_arch_get_scratch_gpfn(xc_interface *xch, uint32_t domid,
                                   xen_pfn_t *gpfn);

tools/libs/ctrl/xc_core_arm.c

@@ -66,33 +66,24 @@ xc_core_arch_memory_map_get(xc_interface *xch, struct xc_core_arch_context *unus
 
 static int
 xc_core_arch_map_p2m_rw(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
-                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                        unsigned long *pfnp, int rw)
+                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m, int rw)
 {
     errno = ENOSYS;
     return -1;
 }
 
 int
-xc_core_arch_map_p2m(xc_interface *xch, unsigned int guest_width, xc_dominfo_t *info,
-                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                        unsigned long *pfnp)
+xc_core_arch_map_p2m(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
+                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m)
 {
-    struct domain_info_context _dinfo = { .guest_width = guest_width };
-    struct domain_info_context *dinfo = &_dinfo;
-    return xc_core_arch_map_p2m_rw(xch, dinfo, info,
-                                   live_shinfo, live_p2m, pfnp, 0);
+    return xc_core_arch_map_p2m_rw(xch, dinfo, info, live_shinfo, live_p2m, 0);
 }
 
 int
-xc_core_arch_map_p2m_writable(xc_interface *xch, unsigned int guest_width, xc_dominfo_t *info,
-                              shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                              unsigned long *pfnp)
+xc_core_arch_map_p2m_writable(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
+                              shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m)
 {
-    struct domain_info_context _dinfo = { .guest_width = guest_width };
-    struct domain_info_context *dinfo = &_dinfo;
-    return xc_core_arch_map_p2m_rw(xch, dinfo, info,
-                                   live_shinfo, live_p2m, pfnp, 1);
+    return xc_core_arch_map_p2m_rw(xch, dinfo, info, live_shinfo, live_p2m, 1);
 }
 
 int

tools/libs/ctrl/xc_core_x86.c

@@ -17,6 +17,7 @@
  *
  */
 
+#include <inttypes.h>
 #include "xc_private.h"
 #include "xc_core.h"
 #include <xen/hvm/e820.h>
@@ -65,35 +66,170 @@ xc_core_arch_memory_map_get(xc_interface *xch, struct xc_core_arch_context *unus
     return 0;
 }
 
-static int
-xc_core_arch_map_p2m_rw(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
-                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                        unsigned long *pfnp, int rw)
+static inline bool is_canonical_address(uint64_t vaddr)
+{
+    return ((int64_t)vaddr >> 47) == ((int64_t)vaddr >> 63);
+}
+
+/* Virtual address ranges reserved for hypervisor. */
+#define HYPERVISOR_VIRT_START_X86_64 0xFFFF800000000000ULL
+#define HYPERVISOR_VIRT_END_X86_64   0xFFFF87FFFFFFFFFFULL
+
+#define HYPERVISOR_VIRT_START_X86_32 0x00000000F5800000ULL
+#define HYPERVISOR_VIRT_END_X86_32   0x00000000FFFFFFFFULL
+
+static xen_pfn_t *
+xc_core_arch_map_p2m_list_rw(xc_interface *xch, struct domain_info_context *dinfo,
+                             uint32_t dom, shared_info_any_t *live_shinfo,
+                             uint64_t p2m_cr3)
+{
+    uint64_t p2m_vaddr, p2m_end, mask, off;
+    xen_pfn_t p2m_mfn, mfn, saved_mfn, max_pfn;
+    uint64_t *ptes = NULL;
+    xen_pfn_t *mfns = NULL;
+    unsigned int fpp, n_pages, level, n_levels, shift,
+                 idx_start, idx_end, idx, saved_idx;
+
+    p2m_vaddr = GET_FIELD(live_shinfo, arch.p2m_vaddr, dinfo->guest_width);
+    fpp = PAGE_SIZE / dinfo->guest_width;
+    dinfo->p2m_frames = (dinfo->p2m_size - 1) / fpp + 1;
+    p2m_end = p2m_vaddr + dinfo->p2m_frames * PAGE_SIZE - 1;
+
+    if ( dinfo->guest_width == 8 )
+    {
+        mask = 0x0000ffffffffffffULL;
+        n_levels = 4;
+        p2m_mfn = p2m_cr3 >> 12;
+        if ( !is_canonical_address(p2m_vaddr) ||
+             !is_canonical_address(p2m_end) ||
+             p2m_end < p2m_vaddr ||
+             (p2m_vaddr <= HYPERVISOR_VIRT_END_X86_64 &&
+              p2m_end > HYPERVISOR_VIRT_START_X86_64) )
+        {
+            ERROR("Bad virtual p2m address range %#" PRIx64 "-%#" PRIx64,
+                  p2m_vaddr, p2m_end);
+            errno = ERANGE;
+            goto out;
+        }
+    }
+    else
+    {
+        mask = 0x00000000ffffffffULL;
+        n_levels = 3;
+        if ( p2m_cr3 & ~mask )
+            p2m_mfn = ~0UL;
+        else
+            p2m_mfn = (uint32_t)((p2m_cr3 >> 12) | (p2m_cr3 << 20));
+        if ( p2m_vaddr > mask || p2m_end > mask || p2m_end < p2m_vaddr ||
+             (p2m_vaddr <= HYPERVISOR_VIRT_END_X86_32 &&
+              p2m_end > HYPERVISOR_VIRT_START_X86_32) )
+        {
+            ERROR("Bad virtual p2m address range %#" PRIx64 "-%#" PRIx64,
+                  p2m_vaddr, p2m_end);
+            errno = ERANGE;
+            goto out;
+        }
+    }
+
+    mfns = malloc(sizeof(*mfns));
+    if ( !mfns )
+    {
+        ERROR("Cannot allocate memory for array of %u mfns", 1);
+        goto out;
+    }
+    mfns[0] = p2m_mfn;
+    off = 0;
+    saved_mfn = 0;
+    idx_start = idx_end = saved_idx = 0;
+
+    for ( level = n_levels; level > 0; level-- )
+    {
+        n_pages = idx_end - idx_start + 1;
+        ptes = xc_map_foreign_pages(xch, dom, PROT_READ, mfns, n_pages);
+        if ( !ptes )
+        {
+            PERROR("Failed to map %u page table pages for p2m list", n_pages);
+            goto out;
+        }
+        free(mfns);
+
+        shift = level * 9 + 3;
+        idx_start = ((p2m_vaddr - off) & mask) >> shift;
+        idx_end = ((p2m_end - off) & mask) >> shift;
+        idx = idx_end - idx_start + 1;
+        mfns = malloc(sizeof(*mfns) * idx);
+        if ( !mfns )
+        {
+            ERROR("Cannot allocate memory for array of %u mfns", idx);
+            goto out;
+        }
+
+        for ( idx = idx_start; idx <= idx_end; idx++ )
+        {
+            mfn = (ptes[idx] & 0x000ffffffffff000ULL) >> PAGE_SHIFT;
+            if ( mfn == 0 )
+            {
+                ERROR("Bad mfn %#lx during page table walk for vaddr %#" PRIx64 " at level %d of p2m list",
+                      mfn, off + ((uint64_t)idx << shift), level);
+                errno = ERANGE;
+                goto out;
+            }
+            mfns[idx - idx_start] = mfn;
+
+            /* Maximum pfn check at level 2. Same reasoning as for p2m tree. */
+            if ( level == 2 )
+            {
+                if ( mfn != saved_mfn )
+                {
+                    saved_mfn = mfn;
+                    saved_idx = idx - idx_start;
+                }
+            }
+        }
+
+        if ( level == 2 )
+        {
+            if ( saved_idx == idx_end )
+                saved_idx++;
+            max_pfn = ((xen_pfn_t)saved_idx << 9) * fpp;
+            if ( max_pfn < dinfo->p2m_size )
+            {
+                dinfo->p2m_size = max_pfn;
+                dinfo->p2m_frames = (dinfo->p2m_size + fpp - 1) / fpp;
+                p2m_end = p2m_vaddr + dinfo->p2m_frames * PAGE_SIZE - 1;
+                idx_end = idx_start + saved_idx;
+            }
+        }
+
+        munmap(ptes, n_pages * PAGE_SIZE);
+        ptes = NULL;
+        off = p2m_vaddr & ((mask >> shift) << shift);
+    }
+
+    return mfns;
+
+ out:
+    free(mfns);
+    if ( ptes )
+        munmap(ptes, n_pages * PAGE_SIZE);
+
+    return NULL;
+}
+
+static xen_pfn_t *
+xc_core_arch_map_p2m_tree_rw(xc_interface *xch, struct domain_info_context *dinfo,
+                             uint32_t dom, shared_info_any_t *live_shinfo)
 {
     /* Double and single indirect references to the live P2M table */
-    xen_pfn_t *live_p2m_frame_list_list = NULL;
+    xen_pfn_t *live_p2m_frame_list_list;
     xen_pfn_t *live_p2m_frame_list = NULL;
     /* Copies of the above. */
     xen_pfn_t *p2m_frame_list_list = NULL;
-    xen_pfn_t *p2m_frame_list = NULL;
+    xen_pfn_t *p2m_frame_list;
 
-    uint32_t dom = info->domid;
-    int ret = -1;
     int err;
     int i;
 
-    if ( xc_domain_nr_gpfns(xch, info->domid, &dinfo->p2m_size) < 0 )
-    {
-        ERROR("Could not get maximum GPFN!");
-        goto out;
-    }
-
-    if ( dinfo->p2m_size < info->nr_pages  )
-    {
-        ERROR("p2m_size < nr_pages -1 (%lx < %lx", dinfo->p2m_size, info->nr_pages - 1);
-        goto out;
-    }
-
     live_p2m_frame_list_list =
         xc_map_foreign_range(xch, dom, PAGE_SIZE, PROT_READ,
                              GET_FIELD(live_shinfo, arch.pfn_to_mfn_frame_list_list, dinfo->guest_width));
@@ -151,22 +287,11 @@ xc_core_arch_map_p2m_rw(xc_interface *xch, struct domain_info_context *dinfo, xc
         for ( i = P2M_FL_ENTRIES - 1; i >= 0; i-- )
             p2m_frame_list[i] = ((uint32_t *)p2m_frame_list)[i];
 
-    *live_p2m = xc_map_foreign_pages(xch, dom,
-                                    rw ? (PROT_READ | PROT_WRITE) : PROT_READ,
-                                    p2m_frame_list,
-                                    P2M_FL_ENTRIES);
+    dinfo->p2m_frames = P2M_FL_ENTRIES;
 
-    if ( !*live_p2m )
-    {
-        PERROR("Couldn't map p2m table");
-        goto out;
-    }
+    return p2m_frame_list;
 
-    *pfnp = dinfo->p2m_size;
-
-    ret = 0;
-
-out:
+ out:
     err = errno;
 
     if ( live_p2m_frame_list_list )
@@ -177,6 +302,57 @@ out:
 
     free(p2m_frame_list_list);
 
+    errno = err;
+
+    return NULL;
+}
+
+static int
+xc_core_arch_map_p2m_rw(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
+                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m, int rw)
+{
+    xen_pfn_t *p2m_frame_list = NULL;
+    uint64_t p2m_cr3;
+    uint32_t dom = info->domid;
+    int ret = -1;
+    int err;
+
+    if ( xc_domain_nr_gpfns(xch, info->domid, &dinfo->p2m_size) < 0 )
+    {
+        ERROR("Could not get maximum GPFN!");
+        goto out;
+    }
+
+    if ( dinfo->p2m_size < info->nr_pages  )
+    {
+        ERROR("p2m_size < nr_pages -1 (%lx < %lx", dinfo->p2m_size, info->nr_pages - 1);
+        goto out;
+    }
+
+    p2m_cr3 = GET_FIELD(live_shinfo, arch.p2m_cr3, dinfo->guest_width);
+
+    p2m_frame_list = p2m_cr3 ? xc_core_arch_map_p2m_list_rw(xch, dinfo, dom, live_shinfo, p2m_cr3)
+                             : xc_core_arch_map_p2m_tree_rw(xch, dinfo, dom, live_shinfo);
+
+    if ( !p2m_frame_list )
+        goto out;
+
+    *live_p2m = xc_map_foreign_pages(xch, dom,
+                                    rw ? (PROT_READ | PROT_WRITE) : PROT_READ,
+                                    p2m_frame_list,
+                                    dinfo->p2m_frames);
+
+    if ( !*live_p2m )
+    {
+        PERROR("Couldn't map p2m table");
+        goto out;
+    }
+
+    ret = 0;
+
+out:
+    err = errno;
+
     free(p2m_frame_list);
 
     errno = err;
@@ -184,25 +360,17 @@ out:
 }
 
 int
-xc_core_arch_map_p2m(xc_interface *xch, unsigned int guest_width, xc_dominfo_t *info,
-                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                        unsigned long *pfnp)
+xc_core_arch_map_p2m(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
+                        shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m)
 {
-    struct domain_info_context _dinfo = { .guest_width = guest_width };
-    struct domain_info_context *dinfo = &_dinfo;
-    return xc_core_arch_map_p2m_rw(xch, dinfo, info,
-                                   live_shinfo, live_p2m, pfnp, 0);
+    return xc_core_arch_map_p2m_rw(xch, dinfo, info, live_shinfo, live_p2m, 0);
 }
 
 int
-xc_core_arch_map_p2m_writable(xc_interface *xch, unsigned int guest_width, xc_dominfo_t *info,
-                              shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
-                              unsigned long *pfnp)
+xc_core_arch_map_p2m_writable(xc_interface *xch, struct domain_info_context *dinfo, xc_dominfo_t *info,
+                              shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m)
 {
-    struct domain_info_context _dinfo = { .guest_width = guest_width };
-    struct domain_info_context *dinfo = &_dinfo;
-    return xc_core_arch_map_p2m_rw(xch, dinfo, info,
-                                   live_shinfo, live_p2m, pfnp, 1);
+    return xc_core_arch_map_p2m_rw(xch, dinfo, info, live_shinfo, live_p2m, 1);
 }
 
 int

tools/libs/ctrl/xc_private.h

@@ -79,6 +79,7 @@ struct iovec {
 
 struct domain_info_context {
     unsigned int guest_width;
+    unsigned int p2m_frames;
     unsigned long p2m_size;
 };
 

tools/libs/guest/xg_domain.c

@@ -24,13 +24,9 @@
 
 int xc_unmap_domain_meminfo(xc_interface *xch, struct xc_domain_meminfo *minfo)
 {
-    struct domain_info_context _di = { .guest_width = minfo->guest_width,
-                                       .p2m_size = minfo->p2m_size};
-    struct domain_info_context *dinfo = &_di;
-
     free(minfo->pfn_type);
     if ( minfo->p2m_table )
-        munmap(minfo->p2m_table, P2M_FL_ENTRIES * PAGE_SIZE);
+        munmap(minfo->p2m_table, minfo->p2m_frames * PAGE_SIZE);
     minfo->p2m_table = NULL;
 
     return 0;
@@ -40,7 +36,6 @@ int xc_map_domain_meminfo(xc_interface *xch, uint32_t domid,
                           struct xc_domain_meminfo *minfo)
 {
     struct domain_info_context _di;
-    struct domain_info_context *dinfo = &_di;
 
     xc_dominfo_t info;
     shared_info_any_t *live_shinfo;
@@ -96,16 +91,16 @@ int xc_map_domain_meminfo(xc_interface *xch, uint32_t domid,
         return -1;
     }
 
-    if ( xc_core_arch_map_p2m_writable(xch, minfo->guest_width, &info,
-                                       live_shinfo, &minfo->p2m_table,
-                                       &minfo->p2m_size) )
+    if ( xc_core_arch_map_p2m_writable(xch, &_di, &info,
+                                       live_shinfo, &minfo->p2m_table) )
     {
         PERROR("Could not map the P2M table");
         munmap(live_shinfo, PAGE_SIZE);
         return -1;
     }
     munmap(live_shinfo, PAGE_SIZE);
-    _di.p2m_size = minfo->p2m_size;
+    minfo->p2m_size = _di.p2m_size;
+    minfo->p2m_frames = _di.p2m_frames;
 
     /* Make space and prepare for getting the PFN types */
     minfo->pfn_type = calloc(sizeof(*minfo->pfn_type), minfo->p2m_size);
@@ -141,7 +136,7 @@ failed:
     }
     if ( minfo->p2m_table )
     {
-        munmap(minfo->p2m_table, P2M_FL_ENTRIES * PAGE_SIZE);
+        munmap(minfo->p2m_table, minfo->p2m_frames * PAGE_SIZE);
         minfo->p2m_table = NULL;
     }