[PATCH v8] x86/altp2m: support for setting restrictions for an array of pages

* [PATCH v8] x86/altp2m: support for setting restrictions for an array of pages
@ 2017-10-24 10:19 Petre Pircalabu
  2017-11-20  9:35 ` Petre Ovidiu PIRCALABU
                   ` (3 more replies)
  0 siblings, 4 replies; 26+ messages in thread
From: Petre Pircalabu @ 2017-10-24 10:19 UTC (permalink / raw)
  To: xen-devel
  Cc: Petre Pircalabu, sstabellini, wei.liu2, Razvan Cojocaru,
	konrad.wilk, George.Dunlap, andrew.cooper3, ian.jackson, tim,
	jbeulich

From: Razvan Cojocaru <rcojocaru@bitdefender.com>

For the default EPT view we have xc_set_mem_access_multi(), which
is able to set an array of pages to an array of access rights with
a single hypercall. However, this functionality was lacking for the
altp2m subsystem, which could only set page restrictions for one
page at a time. This patch addresses the gap.

HVMOP_altp2m_set_mem_access_multi has been added as a HVMOP (as opposed to a
DOMCTL) for consistency with its HVMOP_altp2m_set_mem_access counterpart (and
hence with the original altp2m design, where domains are allowed - with the
proper altp2m access rights - to alter these settings), in the absence of an
official position on the issue from the original altp2m designers.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Signed-off-by: Petre Pircalabu <ppircalabu@bitdefender.com>

---

Changed since v2:
    * Added support for compat arguments translation

Changed since v3:
    * Replaced  __copy_to_guest with __copy_field_to_guest
    * Removed the un-needed parentheses.
    * Fixed xlat.lst ordering
    * Added comment to patch description explaining why the
    functionality was added as an HVMOP.
    * Guard using XEN_GENERATING_COMPAT_HEADERS the hvmmem_type_t definition.
    This will prevent suplicate definitions to be generated for the
    compat equivalent.
    * Added comment describing the manual translation of
    xen_hvm_altp2m_op_t generic fields from compat_hvm_altp2m_op_t.

Changed since v4:
    * Changed the mask parameter to 0x3F.
    * Split long lines.
    * Added "improperly named HVMMEM_(*)" to the comment explaining the
    XEN_GENERATING_COMPAT_HEADERS guard.
    * Removed typedef and XEN_GUEST_HANDLE for xen_hvm_altp2m_set_mem_access_multi.
    * Copied the "opaque" field to guest in compat_altp2m_op.
    * Added build time test to check if the size of
    xen_hvm_altp2m_set_mem_access_multi at least equal to the size of
    compat_hvm_altp2m_set_mem_access_multi.

Changed since v5:
    * Changed the domid parameter type to uint32_t to match 5b42c82f.
    * Added comment to explain why the 0x3F value was chosen.
    * Fixed switch indentation in compat_altp2m_op.
    * Changed the condition used to check if the opaque field has to
    be copied to the guest.
    * Added CHECK_hvm_altp2m_op and CHECK_hvm_altp2m_set_mem_access_multi.

Changed since v6:
    * Removed trailing semicolon from the definitions of CHECK_hvm_altp2m_op
    and CHECK_hvm_altp2m_set_mem_access_multi.
    * Removed BUILD_BUG_ON check.
    * Added comment describing the reason for manually defining the CHECK_
    macros.
    * Added ASSERT_UNREACHABLE as the default switch label action in
    compat_altp2m_op.
    * Added ASSERT(rc == __HYPERVISOR_hvm_op) to make sure the return
    code was actually sey by hypercall_create_continuation.

Changed since v7:
    * Changed the patch title.
---
 tools/libxc/include/xenctrl.h   |   3 +
 tools/libxc/xc_altp2m.c         |  40 ++++++++++++
 xen/arch/x86/hvm/hvm.c          | 138 +++++++++++++++++++++++++++++++++++++++-
 xen/include/Makefile            |   1 +
 xen/include/public/hvm/hvm_op.h |  36 +++++++++--
 xen/include/xlat.lst            |   1 +
 6 files changed, 213 insertions(+), 6 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 666db0b..f171668 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1974,6 +1974,9 @@ int xc_altp2m_set_mem_access(xc_interface *handle, uint32_t domid,
 int xc_altp2m_change_gfn(xc_interface *handle, uint32_t domid,
                          uint16_t view_id, xen_pfn_t old_gfn,
                          xen_pfn_t new_gfn);
+int xc_altp2m_set_mem_access_multi(xc_interface *handle, uint32_t domid,
+                                   uint16_t view_id, uint8_t *access,
+                                   uint64_t *pages, uint32_t nr);
 
 /** 
  * Mem paging operations.
diff --git a/tools/libxc/xc_altp2m.c b/tools/libxc/xc_altp2m.c
index 07fcd18..e170fe3 100644
--- a/tools/libxc/xc_altp2m.c
+++ b/tools/libxc/xc_altp2m.c
@@ -213,3 +213,43 @@ int xc_altp2m_change_gfn(xc_interface *handle, uint32_t domid,
     return rc;
 }
 
+int xc_altp2m_set_mem_access_multi(xc_interface *xch, uint32_t domid,
+                                   uint16_t view_id, uint8_t *access,
+                                   uint64_t *pages, uint32_t nr)
+{
+    int rc;
+
+    DECLARE_HYPERCALL_BUFFER(xen_hvm_altp2m_op_t, arg);
+    DECLARE_HYPERCALL_BOUNCE(access, nr, XC_HYPERCALL_BUFFER_BOUNCE_IN);
+    DECLARE_HYPERCALL_BOUNCE(pages, nr * sizeof(uint64_t),
+                             XC_HYPERCALL_BUFFER_BOUNCE_IN);
+
+    arg = xc_hypercall_buffer_alloc(xch, arg, sizeof(*arg));
+    if ( arg == NULL )
+        return -1;
+
+    arg->version = HVMOP_ALTP2M_INTERFACE_VERSION;
+    arg->cmd = HVMOP_altp2m_set_mem_access_multi;
+    arg->domain = domid;
+    arg->u.set_mem_access_multi.view = view_id;
+    arg->u.set_mem_access_multi.nr = nr;
+
+    if ( xc_hypercall_bounce_pre(xch, pages) ||
+         xc_hypercall_bounce_pre(xch, access) )
+    {
+        PERROR("Could not bounce memory for HVMOP_altp2m_set_mem_access_multi");
+        return -1;
+    }
+
+    set_xen_guest_handle(arg->u.set_mem_access_multi.pfn_list, pages);
+    set_xen_guest_handle(arg->u.set_mem_access_multi.access_list, access);
+
+    rc = xencall2(xch->xcall, __HYPERVISOR_hvm_op, HVMOP_altp2m,
+		  HYPERCALL_BUFFER_AS_ARG(arg));
+
+    xc_hypercall_buffer_free(xch, arg);
+    xc_hypercall_bounce_post(xch, access);
+    xc_hypercall_bounce_post(xch, pages);
+
+    return rc;
+}
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 205b4cb..02e280d 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -73,6 +73,8 @@
 #include <public/arch-x86/cpuid.h>
 #include <asm/cpuid.h>
 
+#include <compat/hvm/hvm_op.h>
+
 bool_t __read_mostly hvm_enabled;
 
 #ifdef DBG_LEVEL_0
@@ -4451,6 +4453,7 @@ static int do_altp2m_op(
     case HVMOP_altp2m_destroy_p2m:
     case HVMOP_altp2m_switch_p2m:
     case HVMOP_altp2m_set_mem_access:
+    case HVMOP_altp2m_set_mem_access_multi:
     case HVMOP_altp2m_change_gfn:
         break;
     default:
@@ -4568,6 +4571,37 @@ static int do_altp2m_op(
                                     a.u.set_mem_access.view);
         break;
 
+    case HVMOP_altp2m_set_mem_access_multi:
+        if ( a.u.set_mem_access_multi.pad ||
+             a.u.set_mem_access_multi.opaque >= a.u.set_mem_access_multi.nr )
+        {
+            rc = -EINVAL;
+            break;
+        }
+
+        /*
+         * The mask was set (arbitrary) to 0x3F to match the value used for
+         * MEMOP, despite the fact there are no encoding limitations for the
+         * start parameter.
+         */
+        rc = p2m_set_mem_access_multi(d, a.u.set_mem_access_multi.pfn_list,
+                                      a.u.set_mem_access_multi.access_list,
+                                      a.u.set_mem_access_multi.nr,
+                                      a.u.set_mem_access_multi.opaque,
+                                      0x3F,
+                                      a.u.set_mem_access_multi.view);
+        if ( rc > 0 )
+        {
+            a.u.set_mem_access_multi.opaque = rc;
+            if ( __copy_field_to_guest(guest_handle_cast(arg, xen_hvm_altp2m_op_t),
+                                       &a, u.set_mem_access_multi.opaque) )
+                rc = -EFAULT;
+            else
+                rc = hypercall_create_continuation(__HYPERVISOR_hvm_op, "lh",
+                                                   HVMOP_altp2m, arg);
+        }
+        break;
+
     case HVMOP_altp2m_change_gfn:
         if ( a.u.change_gfn.pad1 || a.u.change_gfn.pad2 )
             rc = -EINVAL;
@@ -4586,6 +4620,108 @@ static int do_altp2m_op(
     return rc;
 }
 
+DEFINE_XEN_GUEST_HANDLE(compat_hvm_altp2m_op_t);
+
+/*
+ * Manually define the CHECK_ macros for hvm_altp2m_op and
+ * hvm_altp2m_set_mem_access_multi as the generated versions can't handle
+ * correctly the translation of all fields from compat_(*) to xen_(*).
+ */
+#ifndef CHECK_hvm_altp2m_op
+#define CHECK_hvm_altp2m_op \
+    CHECK_SIZE_(struct, hvm_altp2m_op); \
+    CHECK_FIELD_(struct, hvm_altp2m_op, version); \
+    CHECK_FIELD_(struct, hvm_altp2m_op, cmd); \
+    CHECK_FIELD_(struct, hvm_altp2m_op, domain); \
+    CHECK_FIELD_(struct, hvm_altp2m_op, pad1); \
+    CHECK_FIELD_(struct, hvm_altp2m_op, pad2)
+#endif /* CHECK_hvm_altp2m_op */
+
+#ifndef CHECK_hvm_altp2m_set_mem_access_multi
+#define CHECK_hvm_altp2m_set_mem_access_multi \
+    CHECK_FIELD_(struct, hvm_altp2m_set_mem_access_multi, view); \
+    CHECK_FIELD_(struct, hvm_altp2m_set_mem_access_multi, pad); \
+    CHECK_FIELD_(struct, hvm_altp2m_set_mem_access_multi, nr); \
+    CHECK_FIELD_(struct, hvm_altp2m_set_mem_access_multi, opaque)
+#endif /* CHECK_hvm_altp2m_set_mem_access_multi */
+
+CHECK_hvm_altp2m_op;
+CHECK_hvm_altp2m_set_mem_access_multi;
+
+static int compat_altp2m_op(
+    XEN_GUEST_HANDLE_PARAM(void) arg)
+{
+    int rc = 0;
+    struct compat_hvm_altp2m_op a;
+    union
+    {
+        XEN_GUEST_HANDLE_PARAM(void) hnd;
+        struct xen_hvm_altp2m_op *altp2m_op;
+    } nat;
+
+    if ( !hvm_altp2m_supported() )
+        return -EOPNOTSUPP;
+
+    if ( copy_from_guest(&a, arg, 1) )
+        return -EFAULT;
+
+    if ( a.pad1 || a.pad2 ||
+         (a.version != HVMOP_ALTP2M_INTERFACE_VERSION) )
+        return -EINVAL;
+
+    set_xen_guest_handle(nat.hnd, COMPAT_ARG_XLAT_VIRT_BASE);
+
+    switch ( a.cmd )
+    {
+    case HVMOP_altp2m_set_mem_access_multi:
+#define XLAT_hvm_altp2m_set_mem_access_multi_HNDL_pfn_list(_d_, _s_); \
+        guest_from_compat_handle((_d_)->pfn_list, (_s_)->pfn_list)
+#define XLAT_hvm_altp2m_set_mem_access_multi_HNDL_access_list(_d_, _s_); \
+        guest_from_compat_handle((_d_)->access_list, (_s_)->access_list)
+        XLAT_hvm_altp2m_set_mem_access_multi(&nat.altp2m_op->u.set_mem_access_multi,
+                                             &a.u.set_mem_access_multi);
+#undef XLAT_hvm_altp2m_set_mem_access_multi_HNDL_pfn_list
+#undef XLAT_hvm_altp2m_set_mem_access_multi_HNDL_access_list
+        break;
+    default:
+        return do_altp2m_op(arg);
+    }
+
+    /* Manually fill the common part of the xen_hvm_altp2m_op structure. */
+    nat.altp2m_op->version  = a.version;
+    nat.altp2m_op->cmd      = a.cmd;
+    nat.altp2m_op->domain   = a.domain;
+    nat.altp2m_op->pad1     = a.pad1;
+    nat.altp2m_op->pad2     = a.pad2;
+
+    rc = do_altp2m_op(nat.hnd);
+
+    switch ( a.cmd )
+    {
+    case HVMOP_altp2m_set_mem_access_multi:
+        /*
+         * The return code can be positive only if it is the return value
+         * of hypercall_create_continuation. In this case, the opaque value
+         * must be copied back to the guest.
+         */
+        if ( rc > 0 )
+        {
+            ASSERT(rc == __HYPERVISOR_hvm_op);
+            a.u.set_mem_access_multi.opaque =
+                nat.altp2m_op->u.set_mem_access_multi.opaque;
+            if ( __copy_field_to_guest(guest_handle_cast(arg,
+                                                         compat_hvm_altp2m_op_t),
+                                       &a, u.set_mem_access_multi.opaque) )
+                rc = -EFAULT;
+        }
+        break;
+    default:
+        ASSERT_UNREACHABLE();
+    }
+
+    return rc;
+}
+
 static int hvmop_get_mem_type(
     XEN_GUEST_HANDLE_PARAM(xen_hvm_get_mem_type_t) arg)
 {
@@ -4733,7 +4869,7 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
         break;
 
     case HVMOP_altp2m:
-        rc = do_altp2m_op(arg);
+        rc = current->hcall_compat ? compat_altp2m_op(arg) : do_altp2m_op(arg);
         break;
 
     default:
diff --git a/xen/include/Makefile b/xen/include/Makefile
index 1299b19..8fc6e2b 100644
--- a/xen/include/Makefile
+++ b/xen/include/Makefile
@@ -28,6 +28,7 @@ headers-$(CONFIG_X86)     += compat/arch-x86/xen.h
 headers-$(CONFIG_X86)     += compat/arch-x86/xen-$(compat-arch-y).h
 headers-$(CONFIG_X86)     += compat/hvm/hvm_vcpu.h
 headers-$(CONFIG_X86)     += compat/hvm/dm_op.h
+headers-$(CONFIG_X86)     += compat/hvm/hvm_op.h
 headers-y                 += compat/arch-$(compat-arch-y).h compat/pmu.h compat/xlat.h
 headers-$(CONFIG_FLASK)   += compat/xsm/flask_op.h
 
diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h
index 0bdafdf..12de88ac 100644
--- a/xen/include/public/hvm/hvm_op.h
+++ b/xen/include/public/hvm/hvm_op.h
@@ -83,6 +83,13 @@ DEFINE_XEN_GUEST_HANDLE(xen_hvm_set_pci_link_route_t);
 /* Flushes all VCPU TLBs: @arg must be NULL. */
 #define HVMOP_flush_tlbs          5
 
+/*
+ * hvmmem_type_t should not be defined when generating the corresponding
+ * compat header. This will ensure that the improperly named HVMMEM_(*)
+ * values are defined only once.
+ */
+#ifndef XEN_GENERATING_COMPAT_HEADERS
+
 typedef enum {
     HVMMEM_ram_rw,             /* Normal read/write guest RAM */
     HVMMEM_ram_ro,             /* Read-only; writes are discarded */
@@ -102,6 +109,8 @@ typedef enum {
                                   to HVMMEM_ram_rw. */
 } hvmmem_type_t;
 
+#endif /* XEN_GENERATING_COMPAT_HEADERS */
+
 /* Hint from PV drivers for pagetable destruction. */
 #define HVMOP_pagetable_dying        9
 struct xen_hvm_pagetable_dying {
@@ -237,6 +246,20 @@ struct xen_hvm_altp2m_set_mem_access {
 typedef struct xen_hvm_altp2m_set_mem_access xen_hvm_altp2m_set_mem_access_t;
 DEFINE_XEN_GUEST_HANDLE(xen_hvm_altp2m_set_mem_access_t);
 
+struct xen_hvm_altp2m_set_mem_access_multi {
+    /* view */
+    uint16_t view;
+    uint16_t pad;
+    /* Number of pages */
+    uint32_t nr;
+    /* Used for continuation purposes */
+    uint64_t opaque;
+    /* List of pfns to set access for */
+    XEN_GUEST_HANDLE(const_uint64) pfn_list;
+    /* Corresponding list of access settings for pfn_list */
+    XEN_GUEST_HANDLE(const_uint8) access_list;
+};
+
 struct xen_hvm_altp2m_change_gfn {
     /* view */
     uint16_t view;
@@ -268,15 +291,18 @@ struct xen_hvm_altp2m_op {
 #define HVMOP_altp2m_set_mem_access       7
 /* Change a p2m entry to have a different gfn->mfn mapping */
 #define HVMOP_altp2m_change_gfn           8
+/* Set access for an array of pages */
+#define HVMOP_altp2m_set_mem_access_multi 9
     domid_t domain;
     uint16_t pad1;
     uint32_t pad2;
     union {
-        struct xen_hvm_altp2m_domain_state       domain_state;
-        struct xen_hvm_altp2m_vcpu_enable_notify enable_notify;
-        struct xen_hvm_altp2m_view               view;
-        struct xen_hvm_altp2m_set_mem_access     set_mem_access;
-        struct xen_hvm_altp2m_change_gfn         change_gfn;
+        struct xen_hvm_altp2m_domain_state         domain_state;
+        struct xen_hvm_altp2m_vcpu_enable_notify   enable_notify;
+        struct xen_hvm_altp2m_view                 view;
+        struct xen_hvm_altp2m_set_mem_access       set_mem_access;
+        struct xen_hvm_altp2m_change_gfn           change_gfn;
+        struct xen_hvm_altp2m_set_mem_access_multi set_mem_access_multi;
         uint8_t pad[64];
     } u;
 };
diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
index 4346cbe..e3fb0c1 100644
--- a/xen/include/xlat.lst
+++ b/xen/include/xlat.lst
@@ -71,6 +71,7 @@
 ?	dm_op_set_pci_intx_level	hvm/dm_op.h
 ?	dm_op_set_pci_link_route	hvm/dm_op.h
 ?	dm_op_track_dirty_vram		hvm/dm_op.h
+!	hvm_altp2m_set_mem_access_multi	hvm/hvm_op.h
 ?	vcpu_hvm_context		hvm/hvm_vcpu.h
 ?	vcpu_hvm_x86_32			hvm/hvm_vcpu.h
 ?	vcpu_hvm_x86_64			hvm/hvm_vcpu.h
-- 
2.7.4


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