[PATCH for-4.19? v6 0/9] x86: Make MAX_ALTP2M configurable

[PATCH for-4.19? v6 0/9] x86: Make MAX_ALTP2M configurable

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

This series introduces the ability to configure the maximum number of altp2m
tables during domain creation. Previously, the limits were hardcoded to a
maximum of 10. This change allows for greater flexibility in environments that
require more or fewer altp2m views.

This enhancement is particularly relevant for users leveraging Xen's features
for virtual machine introspection.

Changes since v5:
- Reverted "Introduction of accessor functions for altp2m arrays and
  refactoring the code to use them."
  - Reason is minimizing the code changes, and save the code consistency.
  - I've addressed (hopefully all) issues with long lines and mismatched
    _nospec replacements mentioned in previous reviews.
- Removed "struct domain *d" from altp2m_vcpu_initialise/destroy.

Changes since v4:
- Rebased on top of staging (applying Roger's changes).
- Fix mixed tabs/spaces in xenctrl_stubs.c.
- Add missing OCaml bindings for altp2m_opts.
- Substitute altp2m_opts into an unnamed structure. (This is a preparation for
  the next patch that will introduce the `nr` field.)
- altp2m.opts is then shortened to uint16_t and a new field altp2m.nr is added -
  also uint16_t. This value is then verified by libxl to not exceed the maximum
  uint16_t value.

  This puts a hard limit to number of altp2m to 65535, which is enough, at least
  for the time being. Also, altp2m.opts currently uses only 2 bits. Therefore
  I believe this change is justified.
- Introduction of accessor functions for altp2m arrays and refactoring the code
  to use them.
- Added a check to arm/arch_sanitise_domain_config() to disallow creating
  domains with altp2m.nr != 0.
- Added dummy hvm_altp2m_supported() to avoid build errors when CONFIG_HVM is
  disabled.
- Finally, expose altp2m_count to OCaml bindings (and verify both altp2m_opts
  and altp2m_count fit uint16_t).
- I also removed Christian Lindig from the Acked-by, since I think this change
  is significant enough to require a re-review.

Changes since v3:
- Rebased on top of staging (some functions were moved to altp2m.c).
- Re-added the array_index_nospec() where it was removed.

Changes since v2:
- Changed max_altp2m to nr_altp2m.
- Moved arch-dependent check from xen/common/domain.c to xen/arch/x86/domain.c.
- Replaced min(d->nr_altp2m, MAX_EPTP) occurences for just d->nr_altp2m.
- Replaced array_index_nospec(altp2m_idx, ...) for just altp2m_idx.
- Shortened long lines.
- Removed unnecessary comments in altp2m_vcpu_initialise/destroy.
- Moved nr_altp2m field after max_ fields in xen_domctl_createdomain.
- Removed the commit that adjusted the initial allocation of pages from 256
  to 1024. This means that after these patches, technically, the nr_altp2m will
  be capped to (256 - 1 - vcpus - MAX_NESTEDP2M) instead of MAX_EPTP (512).
  Future work will be needed to fix this.

Petr Beneš (9):
  tools/ocaml: Fix mixed tabs/spaces
  tools/ocaml: Add missing ocaml bindings for altp2m_opts
  xen: Refactor altp2m options into a structured format
  tools/xl: Add altp2m_count parameter
  docs/man: Add altp2m_count parameter to the xl.cfg manual
  xen: Make the maximum number of altp2m views configurable for x86
  tools/libxl: Activate the altp2m_count feature
  xen/x86: Disallow creating domains with altp2m enabled and altp2m.nr
    == 0
  tools/ocaml: Add altp2m_count parameter

 docs/man/xl.cfg.5.pod.in             | 14 ++++++
 tools/golang/xenlight/helpers.gen.go |  2 +
 tools/golang/xenlight/types.gen.go   |  1 +
 tools/include/libxl.h                |  8 ++++
 tools/libs/light/libxl_create.c      | 19 +++++++--
 tools/libs/light/libxl_types.idl     |  1 +
 tools/ocaml/libs/xc/xenctrl.ml       |  2 +
 tools/ocaml/libs/xc/xenctrl.mli      |  2 +
 tools/ocaml/libs/xc/xenctrl_stubs.c  | 40 +++++++++++------
 tools/xl/xl_parse.c                  |  9 ++++
 xen/arch/arm/domain.c                |  2 +-
 xen/arch/x86/domain.c                | 45 +++++++++++++++----
 xen/arch/x86/hvm/hvm.c               | 10 ++++-
 xen/arch/x86/hvm/vmx/vmx.c           |  2 +-
 xen/arch/x86/include/asm/domain.h    |  9 ++--
 xen/arch/x86/include/asm/hvm/hvm.h   |  5 +++
 xen/arch/x86/include/asm/p2m.h       |  4 +-
 xen/arch/x86/mm/altp2m.c             | 64 ++++++++++++++++++----------
 xen/arch/x86/mm/hap/hap.c            |  6 +--
 xen/arch/x86/mm/mem_access.c         | 14 +++---
 xen/arch/x86/mm/mem_sharing.c        |  2 +-
 xen/arch/x86/mm/p2m-ept.c            |  7 +--
 xen/arch/x86/mm/p2m.c                |  8 ++--
 xen/common/domain.c                  |  1 +
 xen/include/public/domctl.h          |  7 ++-
 xen/include/xen/sched.h              |  2 +
 26 files changed, 210 insertions(+), 76 deletions(-)

--
2.34.1

[PATCH for-4.19? v6 1/9] tools/ocaml: Fix mixed tabs/spaces

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

No functional change.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
---
 tools/ocaml/libs/xc/xenctrl_stubs.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index c6da9bb091..e86c455802 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -138,12 +138,12 @@ static void domain_handle_of_uuid_string(xen_domain_handle_t h,
  * integers in the Ocaml ABI for more idiomatic handling.
  */
 static value c_bitmap_to_ocaml_list
-             /* ! */
-             /*
+	     /* ! */
+	     /*
 	      * All calls to this function must be in a form suitable
 	      * for xenctrl_abi_check.  The parsing there is ad-hoc.
 	      */
-             (unsigned int bitmap)
+	         (unsigned int bitmap)
 {
 	CAMLparam0();
 	CAMLlocal2(list, tmp);
@@ -180,8 +180,8 @@ static value c_bitmap_to_ocaml_list
 }

 static unsigned int ocaml_list_to_c_bitmap(value l)
-             /* ! */
-             /*
+	     /* ! */
+	     /*
 	      * All calls to this function must be in a form suitable
 	      * for xenctrl_abi_check.  The parsing there is ad-hoc.
 	      */
@@ -259,7 +259,7 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 		/* Quick & dirty check for ABI changes. */
 		BUILD_BUG_ON(sizeof(cfg) != 68);

-        /* Mnemonics for the named fields inside xen_x86_arch_domainconfig */
+		/* Mnemonics for the named fields inside xen_x86_arch_domainconfig */
 #define VAL_EMUL_FLAGS          Field(arch_domconfig, 0)
 #define VAL_MISC_FLAGS          Field(arch_domconfig, 1)

@@ -351,7 +351,7 @@ static value dom_op(value xch_val, value domid,
 	caml_enter_blocking_section();
 	result = fn(xch, c_domid);
 	caml_leave_blocking_section();
-        if (result)
+	if (result)
 		failwith_xc(xch);
 	CAMLreturn(Val_unit);
 }
@@ -383,7 +383,7 @@ CAMLprim value stub_xc_domain_resume_fast(value xch_val, value domid)
 	caml_enter_blocking_section();
 	result = xc_domain_resume(xch, c_domid, 1);
 	caml_leave_blocking_section();
-        if (result)
+	if (result)
 		failwith_xc(xch);
 	CAMLreturn(Val_unit);
 }
@@ -426,7 +426,7 @@ static value alloc_domaininfo(xc_domaininfo_t * info)
 	Store_field(result, 13, Val_int(info->max_vcpu_id));
 	Store_field(result, 14, caml_copy_int32(info->ssidref));

-        tmp = caml_alloc_small(16, 0);
+	tmp = caml_alloc_small(16, 0);
 	for (i = 0; i < 16; i++) {
 		Field(tmp, i) = Val_int(info->handle[i]);
 	}
--
2.34.1

[PATCH for-4.19? v6 2/9] tools/ocaml: Add missing ocaml bindings for altp2m_opts

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Fixes: 0291089f6ea8 ("xen: enable altp2m at create domain domctl")

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
---
 tools/ocaml/libs/xc/xenctrl.ml      | 1 +
 tools/ocaml/libs/xc/xenctrl.mli     | 1 +
 tools/ocaml/libs/xc/xenctrl_stubs.c | 9 ++++++---
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 55923857ec..2690f9a923 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -85,6 +85,7 @@ type domctl_create_config =
     max_grant_frames: int;
     max_maptrack_frames: int;
     max_grant_version: int;
+    altp2m_opts: int32;
     vmtrace_buf_kb: int32;
     cpupool_id: int32;
     arch: arch_domainconfig;
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index 9b4b45db3a..febbe1f6ae 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -77,6 +77,7 @@ type domctl_create_config = {
   max_grant_frames: int;
   max_maptrack_frames: int;
   max_grant_version: int;
+  altp2m_opts: int32;
   vmtrace_buf_kb: int32;
   cpupool_id: int32;
   arch: arch_domainconfig;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index e86c455802..a529080129 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -210,9 +210,10 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 #define VAL_MAX_GRANT_FRAMES    Field(config, 6)
 #define VAL_MAX_MAPTRACK_FRAMES Field(config, 7)
 #define VAL_MAX_GRANT_VERSION   Field(config, 8)
-#define VAL_VMTRACE_BUF_KB      Field(config, 9)
-#define VAL_CPUPOOL_ID          Field(config, 10)
-#define VAL_ARCH                Field(config, 11)
+#define VAL_ALTP2M_OPTS         Field(config, 9)
+#define VAL_VMTRACE_BUF_KB      Field(config, 10)
+#define VAL_CPUPOOL_ID          Field(config, 11)
+#define VAL_ARCH                Field(config, 12)

 	uint32_t domid = Int_val(wanted_domid);
 	uint64_t vmtrace_size = Int32_val(VAL_VMTRACE_BUF_KB);
@@ -230,6 +231,7 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 		.max_maptrack_frames = Int_val(VAL_MAX_MAPTRACK_FRAMES),
 		.grant_opts =
 		    XEN_DOMCTL_GRANT_version(Int_val(VAL_MAX_GRANT_VERSION)),
+		.altp2m_opts = Int32_val(VAL_ALTP2M_OPTS),
 		.vmtrace_size = vmtrace_size,
 		.cpupool_id = Int32_val(VAL_CPUPOOL_ID),
 	};
@@ -288,6 +290,7 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 #undef VAL_ARCH
 #undef VAL_CPUPOOL_ID
 #undef VAL_VMTRACE_BUF_KB
+#undef VAL_ALTP2M_OPTS
 #undef VAL_MAX_GRANT_VERSION
 #undef VAL_MAX_MAPTRACK_FRAMES
 #undef VAL_MAX_GRANT_FRAMES
--
2.34.1

[PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Encapsulate the altp2m options within a struct. This change is preparatory
and sets the groundwork for introducing additional parameter in subsequent
commit.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Julien Grall <jgrall@amazon.com> # arm
Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
---
 tools/libs/light/libxl_create.c     | 6 +++---
 tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
 xen/arch/arm/domain.c               | 2 +-
 xen/arch/x86/domain.c               | 4 ++--
 xen/arch/x86/hvm/hvm.c              | 2 +-
 xen/include/public/domctl.h         | 4 +++-
 6 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index edeadd57ef..569e3d21ed 100644
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -680,17 +680,17 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
         LOG(DETAIL, "altp2m: %s", libxl_altp2m_mode_to_string(b_info->altp2m));
         switch(b_info->altp2m) {
         case LIBXL_ALTP2M_MODE_MIXED:
-            create.altp2m_opts |=
+            create.altp2m.opts |=
                 XEN_DOMCTL_ALTP2M_mode(XEN_DOMCTL_ALTP2M_mixed);
             break;

         case LIBXL_ALTP2M_MODE_EXTERNAL:
-            create.altp2m_opts |=
+            create.altp2m.opts |=
                 XEN_DOMCTL_ALTP2M_mode(XEN_DOMCTL_ALTP2M_external);
             break;

         case LIBXL_ALTP2M_MODE_LIMITED:
-            create.altp2m_opts |=
+            create.altp2m.opts |=
                 XEN_DOMCTL_ALTP2M_mode(XEN_DOMCTL_ALTP2M_limited);
             break;

diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index a529080129..e6c977521f 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -231,7 +231,9 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 		.max_maptrack_frames = Int_val(VAL_MAX_MAPTRACK_FRAMES),
 		.grant_opts =
 		    XEN_DOMCTL_GRANT_version(Int_val(VAL_MAX_GRANT_VERSION)),
-		.altp2m_opts = Int32_val(VAL_ALTP2M_OPTS),
+		.altp2m = {
+			.opts = Int32_val(VAL_ALTP2M_OPTS),
+		},
 		.vmtrace_size = vmtrace_size,
 		.cpupool_id = Int32_val(VAL_CPUPOOL_ID),
 	};
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 8bde2f730d..5234b627d0 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -688,7 +688,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( config->altp2m_opts )
+    if ( config->altp2m.opts )
     {
         dprintk(XENLOG_INFO, "Altp2m not supported\n");
         return -EINVAL;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index ccadfe0c9e..a4f2e7bad1 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -637,7 +637,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
     bool hap = config->flags & XEN_DOMCTL_CDF_hap;
     bool nested_virt = config->flags & XEN_DOMCTL_CDF_nested_virt;
     unsigned int max_vcpus;
-    unsigned int altp2m_mode = MASK_EXTR(config->altp2m_opts,
+    unsigned int altp2m_mode = MASK_EXTR(config->altp2m.opts,
                                          XEN_DOMCTL_ALTP2M_mode_mask);

     if ( hvm ? !hvm_enabled : !IS_ENABLED(CONFIG_PV) )
@@ -717,7 +717,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( config->altp2m_opts & ~XEN_DOMCTL_ALTP2M_mode_mask )
+    if ( config->altp2m.opts & ~XEN_DOMCTL_ALTP2M_mode_mask )
     {
         dprintk(XENLOG_INFO, "Invalid altp2m options selected: %#x\n",
                 config->flags);
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 8334ab1711..a66ebaaceb 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -659,7 +659,7 @@ int hvm_domain_initialise(struct domain *d,
     d->arch.hvm.params[HVM_PARAM_TRIPLE_FAULT_REASON] = SHUTDOWN_reboot;

     /* Set altp2m based on domctl flags. */
-    switch ( MASK_EXTR(config->altp2m_opts, XEN_DOMCTL_ALTP2M_mode_mask) )
+    switch ( MASK_EXTR(config->altp2m.opts, XEN_DOMCTL_ALTP2M_mode_mask) )
     {
     case XEN_DOMCTL_ALTP2M_mixed:
         d->arch.hvm.params[HVM_PARAM_ALTP2M] = XEN_ALTP2M_mixed;
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 2a49fe46ce..dea399aa8e 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -86,6 +86,7 @@ struct xen_domctl_createdomain {

     uint32_t grant_opts;

+    struct {
 /*
  * Enable altp2m mixed mode.
  *
@@ -102,7 +103,8 @@ struct xen_domctl_createdomain {
 /* Altp2m mode signaling uses bits [0, 1]. */
 #define XEN_DOMCTL_ALTP2M_mode_mask  (0x3U)
 #define XEN_DOMCTL_ALTP2M_mode(m)    ((m) & XEN_DOMCTL_ALTP2M_mode_mask)
-    uint32_t altp2m_opts;
+        uint32_t opts;
+    } altp2m;

     /* Per-vCPU buffer size in bytes.  0 to disable. */
     uint32_t vmtrace_size;
--
2.34.1

[PATCH for-4.19? v6 4/9] tools/xl: Add altp2m_count parameter

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Introduce a new altp2m_count parameter to control the maximum number of altp2m
views a domain can use. By default, if altp2m_count is unspecified and altp2m
is enabled, the value is set to 10, reflecting the legacy behavior.

This change is preparatory; it establishes the groundwork for the feature but
does not activate it.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
---
 tools/golang/xenlight/helpers.gen.go | 2 ++
 tools/golang/xenlight/types.gen.go   | 1 +
 tools/include/libxl.h                | 8 ++++++++
 tools/libs/light/libxl_create.c      | 9 +++++++++
 tools/libs/light/libxl_types.idl     | 1 +
 tools/xl/xl_parse.c                  | 9 +++++++++
 6 files changed, 30 insertions(+)

diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index fe5110474d..0449c55f31 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1159,6 +1159,7 @@ if err := x.ArchX86.MsrRelaxed.fromC(&xc.arch_x86.msr_relaxed);err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 x.Altp2M = Altp2MMode(xc.altp2m)
+x.Altp2MCount = uint32(xc.altp2m_count)
 x.VmtraceBufKb = int(xc.vmtrace_buf_kb)
 if err := x.Vpmu.fromC(&xc.vpmu);err != nil {
 return fmt.Errorf("converting field Vpmu: %v", err)
@@ -1676,6 +1677,7 @@ if err := x.ArchX86.MsrRelaxed.toC(&xc.arch_x86.msr_relaxed); err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 xc.altp2m = C.libxl_altp2m_mode(x.Altp2M)
+xc.altp2m_count = C.uint32_t(x.Altp2MCount)
 xc.vmtrace_buf_kb = C.int(x.VmtraceBufKb)
 if err := x.Vpmu.toC(&xc.vpmu); err != nil {
 return fmt.Errorf("converting field Vpmu: %v", err)
diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index c9e45b306f..54607758d3 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -603,6 +603,7 @@ ArchX86 struct {
 MsrRelaxed Defbool
 }
 Altp2M Altp2MMode
+Altp2MCount uint32
 VmtraceBufKb int
 Vpmu Defbool
 }
diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index f5c7167742..bfa06caad2 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -1250,6 +1250,14 @@ typedef struct libxl__ctx libxl_ctx;
  */
 #define LIBXL_HAVE_ALTP2M 1

+/*
+ * LIBXL_HAVE_ALTP2M_COUNT
+ * If this is defined, then libxl supports setting the maximum number of
+ * alternate p2m tables.
+ */
+#define LIBXL_HAVE_ALTP2M_COUNT 1
+#define LIBXL_ALTP2M_COUNT_DEFAULT (~(uint32_t)0)
+
 /*
  * LIBXL_HAVE_REMUS
  * If this is defined, then libxl supports remus.
diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index 569e3d21ed..11d2f282f5 100644
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -482,6 +482,15 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         return -ERROR_INVAL;
     }

+    if (b_info->altp2m_count == LIBXL_ALTP2M_COUNT_DEFAULT) {
+        if ((libxl_defbool_val(b_info->u.hvm.altp2m) ||
+            b_info->altp2m != LIBXL_ALTP2M_MODE_DISABLED))
+            /* Reflect the default legacy count */
+            b_info->altp2m_count = 10;
+        else
+            b_info->altp2m_count = 0;
+    }
+
     /* Assume that providing a bootloader user implies enabling restrict. */
     libxl_defbool_setdefault(&b_info->bootloader_restrict,
                              !!b_info->bootloader_user);
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 4e65e6fda5..2963c5e250 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -729,6 +729,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
     # Alternate p2m is not bound to any architecture or guest type, as it is
     # supported by x86 HVM and ARM support is planned.
     ("altp2m", libxl_altp2m_mode),
+    ("altp2m_count", uint32, {'init_val': 'LIBXL_ALTP2M_COUNT_DEFAULT'}),

     # Size of preallocated vmtrace trace buffers (in KBYTES).
     # Use zero value to disable this feature.
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index e3a4800f6e..a82b8fe6e4 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2063,6 +2063,15 @@ void parse_config_data(const char *config_source,
         }
     }

+    if (!xlu_cfg_get_long(config, "altp2m_count", &l, 1)) {
+        if (l != (uint16_t)l) {
+            fprintf(stderr, "ERROR: invalid value %ld for \"altp2m_count\"\n", l);
+            exit (1);
+        }
+
+        b_info->altp2m_count = l;
+    }
+
     if (!xlu_cfg_get_long(config, "vmtrace_buf_kb", &l, 1) && l) {
         b_info->vmtrace_buf_kb = l;
     }
--
2.34.1

[PATCH for-4.19? v6 5/9] docs/man: Add altp2m_count parameter to the xl.cfg manual

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Update manual pages to include detailed information about the altp2m_count
configuration parameter.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
---
 docs/man/xl.cfg.5.pod.in | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index ac3f88fd57..ff03b43884 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -2039,6 +2039,20 @@ a single guest HVM domain. B<This option is deprecated, use the option
 B<Note>: While the option "altp2mhvm" is deprecated, legacy applications for
 x86 systems will continue to work using it.

+=item B<altp2m_count=NUMBER>
+
+Specifies the maximum number of alternate-p2m views available to the guest.
+This setting is crucial in domain introspection scenarios that require
+multiple physical-to-machine (p2m) memory mappings to be established
+simultaneously.
+
+Enabling multiple p2m views may increase memory usage. It is advisable to
+review and adjust the B<shadow_memory> setting as necessary to accommodate
+the additional memory requirements.
+
+B<Note>: This option is ignored if B<altp2m> is disabled. The default value
+is 10.
+
 =item B<nestedhvm=BOOLEAN>

 Enable or disables guest access to hardware virtualisation features,
--
2.34.1

[PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

This commit introduces the ability to configure the maximum number of altp2m
views for the domain during its creation. Previously, the limits were hardcoded
to a maximum of 10. This change allows for greater flexibility in environments
that require more or fewer altp2m views.

The maximum configurable limit for nr_altp2m on x86 is now set to
MAX_NR_ALTP2M (which currently holds the MAX_EPTP value - 512). This cap is
linked to the architectural limit of the EPTP-switching VMFUNC, which supports
up to 512 entries. Despite there being no inherent need for limiting nr_altp2m
in scenarios not utilizing VMFUNC, decoupling these components would necessitate
substantial code changes.

xen_domctl_createdomain::altp2m is extended for a new field `nr`, that will
configure this limit for a domain. Additionally, previous altp2m.opts value
has been reduced from uint32_t to uint16_t so that both of these fields occupy
as little space as possible.

Accesses to the altp2m_p2m array are modified to respect the new nr_altp2m
value. Accesses to the altp2m_(visible_)eptp arrays are unmodified, since
these arrays always have fixed size of MAX_EPTP.

A dummy hvm_altp2m_supported() function is introduced for non-HVM builds, so
that the compilation won't fail for them.

Additional sanitization is introduced in the x86/arch_sanitise_domain_config
to fix the altp2m.nr value to 10 if it is previously set to 0. This behavior
is only temporary and immediately removed in the upcoming commit (which will
disallow creating a domain with enabled altp2m with zero nr_altp2m).

The reason for this temporary workaround is to retain the legacy behavior
until the feature is fully activated in libxl.

Also, arm/arch_sanitise_domain_config is extended to not allow requesting
non-zero altp2ms.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
---
 xen/arch/arm/domain.c              |  2 +-
 xen/arch/x86/domain.c              | 40 +++++++++++++++----
 xen/arch/x86/hvm/hvm.c             |  8 +++-
 xen/arch/x86/hvm/vmx/vmx.c         |  2 +-
 xen/arch/x86/include/asm/domain.h  |  9 +++--
 xen/arch/x86/include/asm/hvm/hvm.h |  5 +++
 xen/arch/x86/include/asm/p2m.h     |  4 +-
 xen/arch/x86/mm/altp2m.c           | 64 +++++++++++++++++++-----------
 xen/arch/x86/mm/hap/hap.c          |  6 +--
 xen/arch/x86/mm/mem_access.c       | 14 +++----
 xen/arch/x86/mm/mem_sharing.c      |  2 +-
 xen/arch/x86/mm/p2m-ept.c          |  7 ++--
 xen/arch/x86/mm/p2m.c              |  8 ++--
 xen/common/domain.c                |  1 +
 xen/include/public/domctl.h        |  5 ++-
 xen/include/xen/sched.h            |  2 +
 16 files changed, 121 insertions(+), 58 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 5234b627d0..e5785d2d96 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -688,7 +688,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( config->altp2m.opts )
+    if ( config->altp2m.opts || config->altp2m.nr )
     {
         dprintk(XENLOG_INFO, "Altp2m not supported\n");
         return -EINVAL;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index a4f2e7bad1..faec09e15e 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -724,16 +724,42 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( altp2m_mode && nested_virt )
+    if ( altp2m_mode )
     {
-        dprintk(XENLOG_INFO,
-                "Nested virt and altp2m are not supported together\n");
-        return -EINVAL;
-    }
+        if ( nested_virt )
+        {
+            dprintk(XENLOG_INFO,
+                    "Nested virt and altp2m are not supported together\n");
+            return -EINVAL;
+        }
+
+        if ( !hap )
+        {
+            dprintk(XENLOG_INFO, "altp2m is only supported with HAP\n");
+            return -EINVAL;
+        }
+
+        if ( !hvm_altp2m_supported() )
+        {
+            dprintk(XENLOG_INFO, "altp2m is not supported\n");
+            return -EINVAL;
+        }
+
+        if ( !config->altp2m.nr )
+        {
+            /* Fix the value to the legacy default */
+            config->altp2m.nr = 10;
+        }

-    if ( altp2m_mode && !hap )
+        if ( config->altp2m.nr > MAX_NR_ALTP2M )
+        {
+            dprintk(XENLOG_INFO, "altp2m.nr must be <= %lu\n", MAX_NR_ALTP2M);
+            return -EINVAL;
+        }
+    }
+    else if ( config->altp2m.nr )
     {
-        dprintk(XENLOG_INFO, "altp2m is only supported with HAP\n");
+        dprintk(XENLOG_INFO, "altp2m.nr must be zero when altp2m is off\n");
         return -EINVAL;
     }

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index a66ebaaceb..3d0357a0f8 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4657,6 +4657,12 @@ static int do_altp2m_op(
         goto out;
     }

+    if ( d->nr_altp2m == 0 )
+    {
+        rc = -EINVAL;
+        goto out;
+    }
+
     if ( (rc = xsm_hvm_altp2mhvm_op(XSM_OTHER, d, mode, a.cmd)) )
         goto out;

@@ -5245,7 +5251,7 @@ void hvm_fast_singlestep(struct vcpu *v, uint16_t p2midx)
     if ( !hvm_is_singlestep_supported() )
         return;

-    if ( p2midx >= MAX_ALTP2M )
+    if ( p2midx >= v->domain->nr_altp2m )
         return;

     v->arch.hvm.single_step = true;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index f16faa6a61..8548044278 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4885,7 +4885,7 @@ bool asmlinkage vmx_vmenter_helper(const struct cpu_user_regs *regs)
         {
             unsigned int i;

-            for ( i = 0; i < MAX_ALTP2M; ++i )
+            for ( i = 0; i < currd->nr_altp2m; ++i )
             {
                 if ( currd->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
                     continue;
diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
index f5daeb182b..855e844bed 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -258,11 +258,12 @@ struct paging_vcpu {
     struct shadow_vcpu shadow;
 };

-#define MAX_NESTEDP2M 10
+#define MAX_EPTP        (PAGE_SIZE / sizeof(uint64_t))
+#define MAX_NR_ALTP2M   MAX_EPTP
+#define MAX_NESTEDP2M   10

-#define MAX_ALTP2M      10 /* arbitrary */
 #define INVALID_ALTP2M  0xffff
-#define MAX_EPTP        (PAGE_SIZE / sizeof(uint64_t))
+
 struct p2m_domain;
 struct time_scale {
     int shift;
@@ -353,7 +354,7 @@ struct arch_domain

     /* altp2m: allow multiple copies of host p2m */
     bool altp2m_active;
-    struct p2m_domain *altp2m_p2m[MAX_ALTP2M];
+    struct p2m_domain **altp2m_p2m;
     mm_lock_t altp2m_list_lock;
     uint64_t *altp2m_eptp;
     uint64_t *altp2m_visible_eptp;
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h b/xen/arch/x86/include/asm/hvm/hvm.h
index 1c01e22c8e..277648dd18 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -828,6 +828,11 @@ static inline bool hvm_hap_supported(void)
     return false;
 }

+static inline bool hvm_altp2m_supported(void)
+{
+    return false;
+}
+
 static inline bool hvm_nested_virt_supported(void)
 {
     return false;
diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index c1478ffc36..3bf4ce0782 100644
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -886,7 +886,7 @@ static inline struct p2m_domain *p2m_get_altp2m(struct vcpu *v)
     if ( index == INVALID_ALTP2M )
         return NULL;

-    BUG_ON(index >= MAX_ALTP2M);
+    BUG_ON(index >= v->domain->nr_altp2m);

     return v->domain->arch.altp2m_p2m[index];
 }
@@ -896,7 +896,7 @@ static inline bool p2m_set_altp2m(struct vcpu *v, unsigned int idx)
 {
     struct p2m_domain *orig;

-    BUG_ON(idx >= MAX_ALTP2M);
+    BUG_ON(idx >= v->domain->nr_altp2m);

     if ( idx == vcpu_altp2m(v).p2midx )
         return false;
diff --git a/xen/arch/x86/mm/altp2m.c b/xen/arch/x86/mm/altp2m.c
index 6fe1e9ed6b..4ad24de714 100644
--- a/xen/arch/x86/mm/altp2m.c
+++ b/xen/arch/x86/mm/altp2m.c
@@ -15,6 +15,9 @@
 void
 altp2m_vcpu_initialise(struct vcpu *v)
 {
+    if ( v->domain->nr_altp2m == 0 )
+        return;
+
     if ( v != current )
         vcpu_pause(v);

@@ -32,6 +35,9 @@ altp2m_vcpu_destroy(struct vcpu *v)
 {
     struct p2m_domain *p2m;

+    if ( v->domain->nr_altp2m == 0 )
+        return;
+
     if ( v != current )
         vcpu_pause(v);

@@ -122,7 +128,12 @@ int p2m_init_altp2m(struct domain *d)
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);

     mm_lock_init(&d->arch.altp2m_list_lock);
-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    d->arch.altp2m_p2m = xzalloc_array(struct p2m_domain *, d->nr_altp2m);
+
+    if ( !d->arch.altp2m_p2m )
+        return -ENOMEM;
+
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         d->arch.altp2m_p2m[i] = p2m = p2m_init_one(d);
         if ( p2m == NULL )
@@ -143,7 +154,10 @@ void p2m_teardown_altp2m(struct domain *d)
     unsigned int i;
     struct p2m_domain *p2m;

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    if ( !d->arch.altp2m_p2m )
+        return;
+
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( !d->arch.altp2m_p2m[i] )
             continue;
@@ -151,6 +165,8 @@ void p2m_teardown_altp2m(struct domain *d)
         d->arch.altp2m_p2m[i] = NULL;
         p2m_free_one(p2m);
     }
+
+    XFREE(d->arch.altp2m_p2m);
 }

 int altp2m_get_effective_entry(struct p2m_domain *ap2m, gfn_t gfn, mfn_t *mfn,
@@ -200,7 +216,7 @@ bool p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, unsigned int idx)
     struct domain *d = v->domain;
     bool rc = false;

-    if ( idx >= MAX_ALTP2M )
+    if ( idx >= d->nr_altp2m )
         return rc;

     altp2m_list_lock(d);
@@ -306,8 +322,8 @@ static void p2m_reset_altp2m(struct domain *d, unsigned int idx,
 {
     struct p2m_domain *p2m;

-    ASSERT(idx < MAX_ALTP2M);
-    p2m = array_access_nospec(d->arch.altp2m_p2m, idx);
+    ASSERT(idx < d->nr_altp2m);
+    p2m = d->arch.altp2m_p2m[array_index_nospec(idx, d->nr_altp2m)];

     p2m_lock(p2m);

@@ -332,7 +348,7 @@ void p2m_flush_altp2m(struct domain *d)

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         p2m_reset_altp2m(d, i, ALTP2M_DEACTIVATE);
         d->arch.altp2m_eptp[i] = mfn_x(INVALID_MFN);
@@ -348,9 +364,9 @@ static int p2m_activate_altp2m(struct domain *d, unsigned int idx,
     struct p2m_domain *hostp2m, *p2m;
     int rc;

-    ASSERT(idx < MAX_ALTP2M);
+    ASSERT(idx < d->nr_altp2m);

-    p2m = array_access_nospec(d->arch.altp2m_p2m, idx);
+    p2m = d->arch.altp2m_p2m[array_index_nospec(idx, d->nr_altp2m)];
     hostp2m = p2m_get_hostp2m(d);

     p2m_lock(p2m);
@@ -388,7 +404,7 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx)
     int rc = -EINVAL;
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);

-    if ( idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) )
+    if ( idx >= d->nr_altp2m )
         return rc;

     altp2m_list_lock(d);
@@ -415,7 +431,7 @@ int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             continue;
@@ -437,7 +453,7 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx)
     struct p2m_domain *p2m;
     int rc = -EBUSY;

-    if ( !idx || idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) )
+    if ( !idx || idx >= d->nr_altp2m )
         return rc;

     rc = domain_pause_except_self(d);
@@ -450,7 +466,7 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx)
     if ( d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] !=
          mfn_x(INVALID_MFN) )
     {
-        p2m = array_access_nospec(d->arch.altp2m_p2m, idx);
+        p2m = d->arch.altp2m_p2m[array_index_nospec(idx, d->nr_altp2m)];

         if ( !_atomic_read(p2m->active_vcpus) )
         {
@@ -475,7 +491,7 @@ int p2m_switch_domain_altp2m_by_id(struct domain *d, unsigned int idx)
     struct vcpu *v;
     int rc = -EINVAL;

-    if ( idx >= MAX_ALTP2M )
+    if ( idx >= d->nr_altp2m )
         return rc;

     rc = domain_pause_except_self(d);
@@ -510,13 +526,13 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx,
     mfn_t mfn;
     int rc = -EINVAL;

-    if ( idx >=  min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+    if ( idx >= d->nr_altp2m ||
          d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] ==
          mfn_x(INVALID_MFN) )
         return rc;

     hp2m = p2m_get_hostp2m(d);
-    ap2m = array_access_nospec(d->arch.altp2m_p2m, idx);
+    ap2m = d->arch.altp2m_p2m[array_index_nospec(idx, d->nr_altp2m)];

     p2m_lock(hp2m);
     p2m_lock(ap2m);
@@ -572,7 +588,7 @@ int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         p2m_type_t t;
         p2m_access_t a;
@@ -595,7 +611,7 @@ int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,
             else
             {
                 /* At least 2 altp2m's impacted, so reset everything */
-                for ( i = 0; i < MAX_ALTP2M; i++ )
+                for ( i = 0; i < d->nr_altp2m; i++ )
                 {
                     if ( i == last_reset_idx ||
                          d->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
@@ -659,12 +675,13 @@ int p2m_set_suppress_ve_multi(struct domain *d,

     if ( sve->view > 0 )
     {
-        if ( sve->view >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( sve->view >= d->nr_altp2m ||
              d->arch.altp2m_eptp[array_index_nospec(sve->view, MAX_EPTP)] ==
              mfn_x(INVALID_MFN) )
             return -EINVAL;

-        p2m = ap2m = array_access_nospec(d->arch.altp2m_p2m, sve->view);
+        p2m = ap2m =
+            d->arch.altp2m_p2m[array_index_nospec(sve->view, d->nr_altp2m)];
     }

     p2m_lock(host_p2m);
@@ -727,12 +744,13 @@ int p2m_get_suppress_ve(struct domain *d, gfn_t gfn, bool *suppress_ve,

     if ( altp2m_idx > 0 )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              d->arch.altp2m_eptp[array_index_nospec(altp2m_idx, MAX_EPTP)] ==
              mfn_x(INVALID_MFN) )
             return -EINVAL;

-        p2m = ap2m = array_access_nospec(d->arch.altp2m_p2m, altp2m_idx);
+        p2m = ap2m =
+            d->arch.altp2m_p2m[array_index_nospec(altp2m_idx, d->nr_altp2m)];
     }
     else
         p2m = host_p2m;
@@ -763,9 +781,9 @@ int p2m_set_altp2m_view_visibility(struct domain *d, unsigned int altp2m_idx,

     /*
      * Eptp index is correlated with altp2m index and should not exceed
-     * min(MAX_ALTP2M, MAX_EPTP).
+     * d->nr_altp2m.
      */
-    if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+    if ( altp2m_idx >= d->nr_altp2m ||
          d->arch.altp2m_eptp[array_index_nospec(altp2m_idx, MAX_EPTP)] ==
          mfn_x(INVALID_MFN) )
         rc = -EINVAL;
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index d2011fde24..501fd9848b 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -515,7 +515,7 @@ int hap_enable(struct domain *d, u32 mode)
             d->arch.altp2m_visible_eptp[i] = mfn_x(INVALID_MFN);
         }

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             rv = p2m_alloc_table(d->arch.altp2m_p2m[i]);
             if ( rv != 0 )
@@ -538,7 +538,7 @@ void hap_final_teardown(struct domain *d)
     unsigned int i;

     if ( hvm_altp2m_supported() )
-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
             p2m_teardown(d->arch.altp2m_p2m[i], true, NULL);

     /* Destroy nestedp2m's first */
@@ -590,7 +590,7 @@ void hap_teardown(struct domain *d, bool *preempted)
         FREE_XENHEAP_PAGE(d->arch.altp2m_eptp);
         FREE_XENHEAP_PAGE(d->arch.altp2m_visible_eptp);

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             p2m_teardown(d->arch.altp2m_p2m[i], false, preempted);
             if ( preempted && *preempted )
diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index 60a0cce68a..f98408d187 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -347,12 +347,12 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, uint32_t nr,
     /* altp2m view 0 is treated as the hostp2m */
     if ( altp2m_idx )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              d->arch.altp2m_eptp[array_index_nospec(altp2m_idx, MAX_EPTP)] ==
              mfn_x(INVALID_MFN) )
             return -EINVAL;

-        ap2m = array_access_nospec(d->arch.altp2m_p2m, altp2m_idx);
+        ap2m = d->arch.altp2m_p2m[array_index_nospec(altp2m_idx, d->nr_altp2m)];
     }

     if ( !xenmem_access_to_p2m_access(p2m, access, &a) )
@@ -403,12 +403,12 @@ long p2m_set_mem_access_multi(struct domain *d,
     /* altp2m view 0 is treated as the hostp2m */
     if ( altp2m_idx )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              d->arch.altp2m_eptp[array_index_nospec(altp2m_idx, MAX_EPTP)] ==
              mfn_x(INVALID_MFN) )
             return -EINVAL;

-        ap2m = array_access_nospec(d->arch.altp2m_p2m, altp2m_idx);
+        ap2m = d->arch.altp2m_p2m[array_index_nospec(altp2m_idx, d->nr_altp2m)];
     }

     p2m_lock(p2m);
@@ -466,12 +466,12 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn, xenmem_access_t *access,
     }
     else if ( altp2m_idx ) /* altp2m view 0 is treated as the hostp2m */
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              d->arch.altp2m_eptp[array_index_nospec(altp2m_idx, MAX_EPTP)] ==
              mfn_x(INVALID_MFN) )
             return -EINVAL;

-        p2m = array_access_nospec(d->arch.altp2m_p2m, altp2m_idx);
+        p2m = d->arch.altp2m_p2m[array_index_nospec(altp2m_idx, d->nr_altp2m)];
     }

     return _p2m_get_mem_access(p2m, gfn, access);
@@ -486,7 +486,7 @@ void arch_p2m_set_access_required(struct domain *d, bool access_required)
     if ( altp2m_active(d) )
     {
         unsigned int i;
-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             struct p2m_domain *p2m = d->arch.altp2m_p2m[i];

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index da28266ef0..83bb9dd5df 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -912,7 +912,7 @@ static int nominate_page(struct domain *d, gfn_t gfn,

         altp2m_list_lock(d);

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             ap2m = d->arch.altp2m_p2m[i];
             if ( !ap2m )
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index f83610cb8c..69fce28d73 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -1293,7 +1293,7 @@ static void ept_set_ad_sync(struct domain *d, bool value)
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             struct p2m_domain *p2m;

@@ -1500,7 +1500,8 @@ void setup_ept_dump(void)

 void p2m_init_altp2m_ept(struct domain *d, unsigned int i)
 {
-    struct p2m_domain *p2m = array_access_nospec(d->arch.altp2m_p2m, i);
+    struct p2m_domain *p2m =
+        d->arch.altp2m_p2m[array_index_nospec(i, d->nr_altp2m)];
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
     struct ept_data *ept;

@@ -1519,7 +1520,7 @@ unsigned int p2m_find_altp2m_by_eptp(struct domain *d, uint64_t eptp)

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( d->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
             continue;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index e7e327d6a6..ac1d3685f0 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -105,7 +105,7 @@ void p2m_change_entry_type_global(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             {
@@ -140,7 +140,7 @@ void p2m_memory_type_changed(struct domain *d)
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             {
@@ -913,7 +913,7 @@ void p2m_change_type_range(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             {
@@ -986,7 +986,7 @@ int p2m_finish_type_change(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             {
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 67cadb7c3f..776442cec0 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -610,6 +610,7 @@ struct domain *domain_create(domid_t domid,
     if ( config )
     {
         d->options = config->flags;
+        d->nr_altp2m = config->altp2m.nr;
         d->vmtrace_size = config->vmtrace_size;
     }

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index dea399aa8e..056bbc82a2 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -103,7 +103,10 @@ struct xen_domctl_createdomain {
 /* Altp2m mode signaling uses bits [0, 1]. */
 #define XEN_DOMCTL_ALTP2M_mode_mask  (0x3U)
 #define XEN_DOMCTL_ALTP2M_mode(m)    ((m) & XEN_DOMCTL_ALTP2M_mode_mask)
-        uint32_t opts;
+        uint16_t opts;
+
+        /* Number of altp2ms to allocate. */
+        uint16_t nr;
     } altp2m;

     /* Per-vCPU buffer size in bytes.  0 to disable. */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 2dcd1d1a4f..7119f3c44f 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -610,6 +610,8 @@ struct domain
         unsigned int guest_request_sync          : 1;
     } monitor;

+    unsigned int nr_altp2m;    /* Number of altp2m tables */
+
     unsigned int vmtrace_size; /* Buffer size in bytes, or 0 to disable. */

 #ifdef CONFIG_ARGO
--
2.34.1

[PATCH for-4.19? v6 7/9] tools/libxl: Activate the altp2m_count feature

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

This commit activates the previously introduced altp2m_count parameter,
establishing the connection between libxl and Xen.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
---
 tools/libs/light/libxl_create.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index 11d2f282f5..5ad552c4ec 100644
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -656,6 +656,10 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
             .max_grant_frames = b_info->max_grant_frames,
             .max_maptrack_frames = b_info->max_maptrack_frames,
             .grant_opts = XEN_DOMCTL_GRANT_version(b_info->max_grant_version),
+            .altp2m = {
+                .opts = 0, /* .opts will be set below */
+                .nr = b_info->altp2m_count,
+            },
             .vmtrace_size = ROUNDUP(b_info->vmtrace_buf_kb << 10, XC_PAGE_SHIFT),
             .cpupool_id = info->poolid,
         };
--
2.34.1

[PATCH for-4.19? v6 8/9] xen/x86: Disallow creating domains with altp2m enabled and altp2m.nr == 0

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Since libxl finally sends the altp2m.nr value, we can remove the previously
introduced temporary workaround.

Creating domain with enabled altp2m while setting altp2m.nr == 0 doesn't
make sense and it's probably not what user wants.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
 xen/arch/x86/domain.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index faec09e15e..721d753c95 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -747,8 +747,9 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)

         if ( !config->altp2m.nr )
         {
-            /* Fix the value to the legacy default */
-            config->altp2m.nr = 10;
+            dprintk(XENLOG_INFO,
+                    "altp2m must be requested with altp2m.nr > 0\n");
+            return -EINVAL;
         }

         if ( config->altp2m.nr > MAX_NR_ALTP2M )
--
2.34.1

[PATCH for-4.19? v6 9/9] tools/ocaml: Add altp2m_count parameter

[Petr Beneš]

From: Petr Beneš <w1benny@gmail.com>

Allow developers using the OCaml bindings to set the altp2m_count parameter.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
---
 tools/ocaml/libs/xc/xenctrl.ml      |  1 +
 tools/ocaml/libs/xc/xenctrl.mli     |  1 +
 tools/ocaml/libs/xc/xenctrl_stubs.c | 19 +++++++++++++++----
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 2690f9a923..a3e50ac394 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -86,6 +86,7 @@ type domctl_create_config =
     max_maptrack_frames: int;
     max_grant_version: int;
     altp2m_opts: int32;
+    altp2m_count: int32;
     vmtrace_buf_kb: int32;
     cpupool_id: int32;
     arch: arch_domainconfig;
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index febbe1f6ae..b97021d3d2 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -78,6 +78,7 @@ type domctl_create_config = {
   max_maptrack_frames: int;
   max_grant_version: int;
   altp2m_opts: int32;
+  altp2m_count: int32;
   vmtrace_buf_kb: int32;
   cpupool_id: int32;
   arch: arch_domainconfig;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index e6c977521f..78ae4967e6 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -211,13 +211,22 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 #define VAL_MAX_MAPTRACK_FRAMES Field(config, 7)
 #define VAL_MAX_GRANT_VERSION   Field(config, 8)
 #define VAL_ALTP2M_OPTS         Field(config, 9)
-#define VAL_VMTRACE_BUF_KB      Field(config, 10)
-#define VAL_CPUPOOL_ID          Field(config, 11)
-#define VAL_ARCH                Field(config, 12)
+#define VAL_ALTP2M_COUNT        Field(config, 10)
+#define VAL_VMTRACE_BUF_KB      Field(config, 11)
+#define VAL_CPUPOOL_ID          Field(config, 12)
+#define VAL_ARCH                Field(config, 13)

 	uint32_t domid = Int_val(wanted_domid);
+	uint32_t altp2m_opts = Int32_val(VAL_ALTP2M_OPTS);
+	uint32_t altp2m_nr = Int32_val(VAL_ALTP2M_COUNT);
 	uint64_t vmtrace_size = Int32_val(VAL_VMTRACE_BUF_KB);

+	if ( altp2m_opts != (uint16_t)altp2m_opts )
+		caml_invalid_argument("altp2m_opts");
+
+	if ( altp2m_nr != (uint16_t)altp2m_nr )
+		caml_invalid_argument("altp2m_count");
+
 	vmtrace_size = ROUNDUP(vmtrace_size << 10, XC_PAGE_SHIFT);
 	if ( vmtrace_size != (uint32_t)vmtrace_size )
 		caml_invalid_argument("vmtrace_buf_kb");
@@ -232,7 +241,8 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 		.grant_opts =
 		    XEN_DOMCTL_GRANT_version(Int_val(VAL_MAX_GRANT_VERSION)),
 		.altp2m = {
-			.opts = Int32_val(VAL_ALTP2M_OPTS),
+			.opts = altp2m_opts,
+			.nr = altp2m_nr,
 		},
 		.vmtrace_size = vmtrace_size,
 		.cpupool_id = Int32_val(VAL_CPUPOOL_ID),
@@ -292,6 +302,7 @@ CAMLprim value stub_xc_domain_create(value xch_val, value wanted_domid, value co
 #undef VAL_ARCH
 #undef VAL_CPUPOOL_ID
 #undef VAL_VMTRACE_BUF_KB
+#undef VAL_ALTP2M_COUNT
 #undef VAL_ALTP2M_OPTS
 #undef VAL_MAX_GRANT_VERSION
 #undef VAL_MAX_MAPTRACK_FRAMES
--
2.34.1

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Jan Beulich]

On 10.06.2024 19:10, Petr Beneš wrote:
> From: Petr Beneš <w1benny@gmail.com>
> 
> Encapsulate the altp2m options within a struct. This change is preparatory
> and sets the groundwork for introducing additional parameter in subsequent
> commit.
> 
> Signed-off-by: Petr Beneš <w1benny@gmail.com>
> Acked-by: Julien Grall <jgrall@amazon.com> # arm
> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor

Looks like you lost Christian's ack for ...

> ---
>  tools/libs/light/libxl_create.c     | 6 +++---
>  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-

... the adjustment of this file?

Jan

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Petr Beneš]

On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 10.06.2024 19:10, Petr Beneš wrote:
> > From: Petr Beneš <w1benny@gmail.com>
> >
> > Encapsulate the altp2m options within a struct. This change is preparatory
> > and sets the groundwork for introducing additional parameter in subsequent
> > commit.
> >
> > Signed-off-by: Petr Beneš <w1benny@gmail.com>
> > Acked-by: Julien Grall <jgrall@amazon.com> # arm
> > Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
>
> Looks like you lost Christian's ack for ...
>
> > ---
> >  tools/libs/light/libxl_create.c     | 6 +++---
> >  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
>
> ... the adjustment of this file?

In the cover email, Christian only acked:

> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---

P.

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Jan Beulich]

On 11.06.2024 10:00, Petr Beneš wrote:
> On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 10.06.2024 19:10, Petr Beneš wrote:
>>> From: Petr Beneš <w1benny@gmail.com>
>>>
>>> Encapsulate the altp2m options within a struct. This change is preparatory
>>> and sets the groundwork for introducing additional parameter in subsequent
>>> commit.
>>>
>>> Signed-off-by: Petr Beneš <w1benny@gmail.com>
>>> Acked-by: Julien Grall <jgrall@amazon.com> # arm
>>> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
>>
>> Looks like you lost Christian's ack for ...
>>
>>> ---
>>>  tools/libs/light/libxl_create.c     | 6 +++---
>>>  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
>>
>> ... the adjustment of this file?
> 
> In the cover email, Christian only acked:
> 
>> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
>> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
>> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---

Right, but above I was talking about the last of these three files.

Jan

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Petr Beneš]

On Tue, Jun 11, 2024 at 11:14 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 11.06.2024 10:00, Petr Beneš wrote:
> > On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>
> >> On 10.06.2024 19:10, Petr Beneš wrote:
> >>> From: Petr Beneš <w1benny@gmail.com>
> >>>
> >>> Encapsulate the altp2m options within a struct. This change is preparatory
> >>> and sets the groundwork for introducing additional parameter in subsequent
> >>> commit.
> >>>
> >>> Signed-off-by: Petr Beneš <w1benny@gmail.com>
> >>> Acked-by: Julien Grall <jgrall@amazon.com> # arm
> >>> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
> >>
> >> Looks like you lost Christian's ack for ...
> >>
> >>> ---
> >>>  tools/libs/light/libxl_create.c     | 6 +++---
> >>>  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
> >>
> >> ... the adjustment of this file?
> >
> > In the cover email, Christian only acked:
> >
> >> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
> >> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
> >> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---
>
> Right, but above I was talking about the last of these three files.
>
> Jan

Ouch. It didn't occur to me that Ack on cover email acks each of the
files in every separate patch. My thinking was it acks only the
patches where those three are together. Anyway, it makes sense. I'll
resend v7.

P.

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Jan Beulich]

On 11.06.2024 11:34, Petr Beneš wrote:
> On Tue, Jun 11, 2024 at 11:14 AM Jan Beulich <jbeulich@suse.com> wrote:
>> On 11.06.2024 10:00, Petr Beneš wrote:
>>> On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>> On 10.06.2024 19:10, Petr Beneš wrote:
>>>>> From: Petr Beneš <w1benny@gmail.com>
>>>>>
>>>>> Encapsulate the altp2m options within a struct. This change is preparatory
>>>>> and sets the groundwork for introducing additional parameter in subsequent
>>>>> commit.
>>>>>
>>>>> Signed-off-by: Petr Beneš <w1benny@gmail.com>
>>>>> Acked-by: Julien Grall <jgrall@amazon.com> # arm
>>>>> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
>>>>
>>>> Looks like you lost Christian's ack for ...
>>>>
>>>>> ---
>>>>>  tools/libs/light/libxl_create.c     | 6 +++---
>>>>>  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
>>>>
>>>> ... the adjustment of this file?
>>>
>>> In the cover email, Christian only acked:
>>>
>>>> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
>>>> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
>>>> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---
>>
>> Right, but above I was talking about the last of these three files.
>>
>> Jan
> 
> Ouch. It didn't occur to me that Ack on cover email acks each of the
> files in every separate patch. My thinking was it acks only the
> patches where those three are together. Anyway, it makes sense. I'll
> resend v7.

Well, no need to just for this. Yet if a v7 turns out necessary, please
make sure you have the ack recorded.

Jan

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Petr Beneš]

On Tue, Jun 11, 2024 at 11:36 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 11.06.2024 11:34, Petr Beneš wrote:
> > On Tue, Jun 11, 2024 at 11:14 AM Jan Beulich <jbeulich@suse.com> wrote:
> >> On 11.06.2024 10:00, Petr Beneš wrote:
> >>> On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>>> On 10.06.2024 19:10, Petr Beneš wrote:
> >>>>> From: Petr Beneš <w1benny@gmail.com>
> >>>>>
> >>>>> Encapsulate the altp2m options within a struct. This change is preparatory
> >>>>> and sets the groundwork for introducing additional parameter in subsequent
> >>>>> commit.
> >>>>>
> >>>>> Signed-off-by: Petr Beneš <w1benny@gmail.com>
> >>>>> Acked-by: Julien Grall <jgrall@amazon.com> # arm
> >>>>> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
> >>>>
> >>>> Looks like you lost Christian's ack for ...
> >>>>
> >>>>> ---
> >>>>>  tools/libs/light/libxl_create.c     | 6 +++---
> >>>>>  tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
> >>>>
> >>>> ... the adjustment of this file?
> >>>
> >>> In the cover email, Christian only acked:
> >>>
> >>>> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
> >>>> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
> >>>> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---
> >>
> >> Right, but above I was talking about the last of these three files.
> >>
> >> Jan
> >
> > Ouch. It didn't occur to me that Ack on cover email acks each of the
> > files in every separate patch. My thinking was it acks only the
> > patches where those three are together. Anyway, it makes sense. I'll
> > resend v7.
>
> Well, no need to just for this. Yet if a v7 turns out necessary, please
> make sure you have the ack recorded.
>
> Jan

Noted.

P.

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Anthony PERARD]

On Mon, Jun 10, 2024 at 05:10:41PM +0000, Petr Beneš wrote:
> From: Petr Beneš <w1benny@gmail.com>
>
> Encapsulate the altp2m options within a struct. This change is preparatory
> and sets the groundwork for introducing additional parameter in subsequent
> commit.
>
> Signed-off-by: Petr Beneš <w1benny@gmail.com>
> Acked-by: Julien Grall <jgrall@amazon.com> # arm
> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
> ---
>  tools/libs/light/libxl_create.c     | 6 +++---

Acked-by: Anthony PERARD <anthony.perard@vates.tech>

Thanks,

--


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Re: [PATCH for-4.19? v6 4/9] tools/xl: Add altp2m_count parameter

[Anthony PERARD]

On Mon, Jun 10, 2024 at 05:10:42PM +0000, Petr Beneš wrote:
> From: Petr Beneš <w1benny@gmail.com>
>
> Introduce a new altp2m_count parameter to control the maximum number of altp2m
> views a domain can use. By default, if altp2m_count is unspecified and altp2m
> is enabled, the value is set to 10, reflecting the legacy behavior.
>
> This change is preparatory; it establishes the groundwork for the feature but
> does not activate it.
>
> Signed-off-by: Petr Beneš <w1benny@gmail.com>
> ---
>  tools/golang/xenlight/helpers.gen.go | 2 ++
>  tools/golang/xenlight/types.gen.go   | 1 +
>  tools/include/libxl.h                | 8 ++++++++
>  tools/libs/light/libxl_create.c      | 9 +++++++++
>  tools/libs/light/libxl_types.idl     | 1 +
>  tools/xl/xl_parse.c                  | 9 +++++++++
>  6 files changed, 30 insertions(+)
>
> diff --git a/tools/include/libxl.h b/tools/include/libxl.h
> index f5c7167742..bfa06caad2 100644
> --- a/tools/include/libxl.h
> +++ b/tools/include/libxl.h
> @@ -1250,6 +1250,14 @@ typedef struct libxl__ctx libxl_ctx;
>   */
>  #define LIBXL_HAVE_ALTP2M 1
>
> +/*
> + * LIBXL_HAVE_ALTP2M_COUNT
> + * If this is defined, then libxl supports setting the maximum number of
> + * alternate p2m tables.
> + */
> +#define LIBXL_HAVE_ALTP2M_COUNT 1
> +#define LIBXL_ALTP2M_COUNT_DEFAULT (~(uint32_t)0)

Can you move this define (LIBXL_ALTP2M_COUNT_DEFAULT) out of the public
header? I don't think this needs to be known to application using libxl
(like xl). You can move it to "libxl_internal.h", I don't think there's
a better place and there's already a few "default" (more like initial
value) define there.

Beside that, the patch looks fine,
so with that change: Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>

Thanks,

--


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Re: [PATCH for-4.19? v6 5/9] docs/man: Add altp2m_count parameter to the xl.cfg manual

[Anthony PERARD]

On Mon, Jun 10, 2024 at 05:10:43PM +0000, Petr Beneš wrote:
> From: Petr Beneš <w1benny@gmail.com>
>
> Update manual pages to include detailed information about the altp2m_count
> configuration parameter.
>
> Signed-off-by: Petr Beneš <w1benny@gmail.com>

Acked-by: Anthony PERARD <anthony.perard@vates.tech>

Thanks,

--


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Re: [PATCH for-4.19? v6 7/9] tools/libxl: Activate the altp2m_count feature

[Anthony PERARD]

On Mon, Jun 10, 2024 at 05:10:45PM +0000, Petr Beneš wrote:
> From: Petr Beneš <w1benny@gmail.com>
>
> This commit activates the previously introduced altp2m_count parameter,
> establishing the connection between libxl and Xen.
>
> Signed-off-by: Petr Beneš <w1benny@gmail.com>

Acked-by: Anthony PERARD <anthony.perard@vates.tech>

Thanks,

--


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Re: [PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Jan Beulich]

On 10.06.2024 19:10, Petr Beneš wrote:
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -724,16 +724,42 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
>          return -EINVAL;
>      }
> 
> -    if ( altp2m_mode && nested_virt )
> +    if ( altp2m_mode )
>      {
> -        dprintk(XENLOG_INFO,
> -                "Nested virt and altp2m are not supported together\n");
> -        return -EINVAL;
> -    }
> +        if ( nested_virt )
> +        {
> +            dprintk(XENLOG_INFO,
> +                    "Nested virt and altp2m are not supported together\n");
> +            return -EINVAL;
> +        }
> +
> +        if ( !hap )
> +        {
> +            dprintk(XENLOG_INFO, "altp2m is only supported with HAP\n");
> +            return -EINVAL;
> +        }
> +
> +        if ( !hvm_altp2m_supported() )
> +        {
> +            dprintk(XENLOG_INFO, "altp2m is not supported\n");
> +            return -EINVAL;
> +        }

Wouldn't this better be first in the group?

> @@ -510,13 +526,13 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx,
>      mfn_t mfn;
>      int rc = -EINVAL;
> 
> -    if ( idx >=  min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
> +    if ( idx >= d->nr_altp2m ||
>           d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] ==

This ends up being suspicious: The range check is against a value different
from what is passed to array_index_nospec(). The two weren't the same
before either, but there the range check was more strict (which now isn't
visible anymore, even though I think it would still be true). Imo this
wants a comment, or an assertion effectively taking the place of a comment.
(I actually wonder whether we really [still] need to allocate a full page
for d->arch.altp2m_eptp.)

> @@ -659,12 +675,13 @@ int p2m_set_suppress_ve_multi(struct domain *d,
> 
>      if ( sve->view > 0 )
>      {
> -        if ( sve->view >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
> +        if ( sve->view >= d->nr_altp2m ||
>               d->arch.altp2m_eptp[array_index_nospec(sve->view, MAX_EPTP)] ==
>               mfn_x(INVALID_MFN) )
>              return -EINVAL;

Same again here and at least twice more further down, and yet more of those
elsewhere. Since they're all "is this slot populated" checks, maybe we want
an is_altp2m_eptp_valid() helper?

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -103,7 +103,10 @@ struct xen_domctl_createdomain {
>  /* Altp2m mode signaling uses bits [0, 1]. */
>  #define XEN_DOMCTL_ALTP2M_mode_mask  (0x3U)
>  #define XEN_DOMCTL_ALTP2M_mode(m)    ((m) & XEN_DOMCTL_ALTP2M_mode_mask)
> -        uint32_t opts;
> +        uint16_t opts;
> +
> +        /* Number of altp2ms to allocate. */
> +        uint16_t nr;
>      } altp2m;

Nit: I wouldn't say "allocate" here, but "permit" or "support" or some such.
Whether any form of per-altp2m allocation is necessary is an implementation
detail.

Jan

Re: [PATCH for-4.19? v6 3/9] xen: Refactor altp2m options into a structured format

[Christian Lindig]

> On 11 Jun 2024, at 10:14, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 11.06.2024 10:00, Petr Beneš wrote:
>> On Tue, Jun 11, 2024 at 8:41 AM Jan Beulich <jbeulich@suse.com> wrote:
>>> 
>>> On 10.06.2024 19:10, Petr Beneš wrote:
>>>> From: Petr Beneš <w1benny@gmail.com>
>>>> 
>>>> Encapsulate the altp2m options within a struct. This change is preparatory
>>>> and sets the groundwork for introducing additional parameter in subsequent
>>>> commit.
>>>> 
>>>> Signed-off-by: Petr Beneš <w1benny@gmail.com>
>>>> Acked-by: Julien Grall <jgrall@amazon.com> # arm
>>>> Reviewed-by: Jan Beulich <jbeulich@suse.com> # hypervisor
>>> 
>>> Looks like you lost Christian's ack for ...
>>> 
>>>> ---
>>>> tools/libs/light/libxl_create.c     | 6 +++---
>>>> tools/ocaml/libs/xc/xenctrl_stubs.c | 4 +++-
>>> 
>>> ... the adjustment of this file?
>> 
>> In the cover email, Christian only acked:
>> 
>>> tools/ocaml/libs/xc/xenctrl.ml       |   2 +
>>> tools/ocaml/libs/xc/xenctrl.mli      |   2 +
>>> tools/ocaml/libs/xc/xenctrl_stubs.c  |  40 +++++++---
> 
> Right, but above I was talking about the last of these three files.
> 
> Jan

Consider all of this Acked by me. I think this email-based workflow when we are going through several iterations are quite a burden.

— C

Re: [PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Petr Beneš]

On Thu, Jun 13, 2024 at 2:03 PM Jan Beulich <jbeulich@suse.com> wrote:
> > @@ -510,13 +526,13 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx,
> >      mfn_t mfn;
> >      int rc = -EINVAL;
> >
> > -    if ( idx >=  min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
> > +    if ( idx >= d->nr_altp2m ||
> >           d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] ==
>
> This ends up being suspicious: The range check is against a value different
> from what is passed to array_index_nospec(). The two weren't the same
> before either, but there the range check was more strict (which now isn't
> visible anymore, even though I think it would still be true). Imo this
> wants a comment, or an assertion effectively taking the place of a comment.

> Since they're all "is this slot populated" checks, maybe we want
> an is_altp2m_eptp_valid() helper?

Let me see if I understand correctly. You're suggesting the condition
should be replaced with something like this? (Also, I would suggest
altp2m_is_eptp_valid() name, since it's consistent e.g. with
p2m_is_altp2m().)

static inline bool altp2m_is_eptp_valid(const struct domain *d,
                                        unsigned int idx)
{
    /*
     * EPTP index is correlated with altp2m index and should not exceed
     * d->nr_altp2m.
     */
    assert(idx < d->nr_altp2m);

    return idx < MAX_EPTP &&
        d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] !=
        mfn_x(INVALID_MFN);
}

Note that in the codebase there are also very similar checks, but
again without array_index_nospec. For instance, in the
p2m_altp2m_propagate_change() function (which is called fairly
frequently):

int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,
                                mfn_t mfn, unsigned int page_order,
                                p2m_type_t p2mt, p2m_access_t p2ma)
{
    struct p2m_domain *p2m;
    unsigned int i;
    unsigned int reset_count = 0;
    unsigned int last_reset_idx = ~0;
    int ret = 0;

    if ( !altp2m_active(d) )
        return 0;

    altp2m_list_lock(d);

    for ( i = 0; i < d->nr_altp2m; i++ )
    {
        p2m_type_t t;
        p2m_access_t a;

        // XXX this could be replaced with altp2m_is_eptp_valid(), but
based on previous review remarks,
        // it would introduce unnecessary perf. hit. So, should these
occurrences left unchanged?
        if ( d->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
            continue;

       ...

There are more instances of this. Which re-opens again the issue from
previous conversation: should I introduce a function which will be
used in some cases (where _nospec is used) and not used elsewhere?

P.

Re: [PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Jan Beulich]

On 19.06.2024 17:46, Petr Beneš wrote:
> On Thu, Jun 13, 2024 at 2:03 PM Jan Beulich <jbeulich@suse.com> wrote:
>>> @@ -510,13 +526,13 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx,
>>>      mfn_t mfn;
>>>      int rc = -EINVAL;
>>>
>>> -    if ( idx >=  min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
>>> +    if ( idx >= d->nr_altp2m ||
>>>           d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] ==
>>
>> This ends up being suspicious: The range check is against a value different
>> from what is passed to array_index_nospec(). The two weren't the same
>> before either, but there the range check was more strict (which now isn't
>> visible anymore, even though I think it would still be true). Imo this
>> wants a comment, or an assertion effectively taking the place of a comment.
> 
>> Since they're all "is this slot populated" checks, maybe we want
>> an is_altp2m_eptp_valid() helper?
> 
> Let me see if I understand correctly. You're suggesting the condition
> should be replaced with something like this? (Also, I would suggest
> altp2m_is_eptp_valid() name, since it's consistent e.g. with
> p2m_is_altp2m().)
> 
> static inline bool altp2m_is_eptp_valid(const struct domain *d,
>                                         unsigned int idx)
> {
>     /*
>      * EPTP index is correlated with altp2m index and should not exceed
>      * d->nr_altp2m.
>      */
>     assert(idx < d->nr_altp2m);
> 
>     return idx < MAX_EPTP &&
>         d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] !=
>         mfn_x(INVALID_MFN);
> }

Not exactly. You may not assert on idx. The assertion, if any, wants to
check d->nr_altp2m against MAX_EPTP.

> Note that in the codebase there are also very similar checks, but
> again without array_index_nospec. For instance, in the
> p2m_altp2m_propagate_change() function (which is called fairly
> frequently):
> 
> int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,
>                                 mfn_t mfn, unsigned int page_order,
>                                 p2m_type_t p2mt, p2m_access_t p2ma)
> {
>     struct p2m_domain *p2m;
>     unsigned int i;
>     unsigned int reset_count = 0;
>     unsigned int last_reset_idx = ~0;
>     int ret = 0;
> 
>     if ( !altp2m_active(d) )
>         return 0;
> 
>     altp2m_list_lock(d);
> 
>     for ( i = 0; i < d->nr_altp2m; i++ )
>     {
>         p2m_type_t t;
>         p2m_access_t a;
> 
>         // XXX this could be replaced with altp2m_is_eptp_valid(), but
> based on previous review remarks,
>         // it would introduce unnecessary perf. hit. So, should these
> occurrences left unchanged?
>         if ( d->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
>             continue;
> 
>        ...
> 
> There are more instances of this. Which re-opens again the issue from
> previous conversation: should I introduce a function which will be
> used in some cases (where _nospec is used) and not used elsewhere?

You're again comparing cases where we control the index (in the loop) with
cases where we don't (hypercall inputs).

Jan

Re: [PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Petr Beneš]

On Thu, Jun 20, 2024 at 9:25 AM Jan Beulich <jbeulich@suse.com> wrote:
> Not exactly. You may not assert on idx. The assertion, if any, wants to
> check d->nr_altp2m against MAX_EPTP.

In addition to the check in arch_sanitize_domain? As a safeguard?

> You're again comparing cases where we control the index (in the loop) with
> cases where we don't (hypercall inputs).

So, replacing strictly the occurrences where we don't control the
index, and leave everything else as is. Okay.

P.

Re: [PATCH for-4.19? v6 6/9] xen: Make the maximum number of altp2m views configurable for x86

[Jan Beulich]

On 21.06.2024 13:40, Petr Beneš wrote:
> On Thu, Jun 20, 2024 at 9:25 AM Jan Beulich <jbeulich@suse.com> wrote:
>> Not exactly. You may not assert on idx. The assertion, if any, wants to
>> check d->nr_altp2m against MAX_EPTP.
> 
> In addition to the check in arch_sanitize_domain? As a safeguard?

Well. Such an assertion can only validly be put anywhere because of the
checking done in arch_sanitize_domain(). You can view such assertions as
both a safeguard and as a comment-like thing.

Jan

Re: [PATCH for-4.19? v6 0/9] x86: Make MAX_ALTP2M configurable

[Jan Beulich]

On 10.06.2024 19:10, Petr Beneš wrote:
> Petr Beneš (9):
>   tools/ocaml: Fix mixed tabs/spaces
>   tools/ocaml: Add missing ocaml bindings for altp2m_opts
>   xen: Refactor altp2m options into a structured format
>   tools/xl: Add altp2m_count parameter
>   docs/man: Add altp2m_count parameter to the xl.cfg manual
>   xen: Make the maximum number of altp2m views configurable for x86
>   tools/libxl: Activate the altp2m_count feature
>   xen/x86: Disallow creating domains with altp2m enabled and altp2m.nr
>     == 0
>   tools/ocaml: Add altp2m_count parameter

While the first two patches did go in, the rest is still pending afaict. If
the series is still deemed relevant, would you please either chase the
missing but necessary acks, or re-submit with review comments addressed (if
any)? If instead it was abandoned, could you please also indicate so?

Thanks, Jan

Re: [PATCH for-4.19? v6 0/9] x86: Make MAX_ALTP2M configurable

[Petr Beneš]

On Wed, Oct 16, 2024 at 12:10 PM Jan Beulich <jbeulich@suse.com> wrote:
> While the first two patches did go in, the rest is still pending afaict. If
> the series is still deemed relevant, would you please either chase the
> missing but necessary acks, or re-submit with review comments addressed (if
> any)? If instead it was abandoned, could you please also indicate so?

I plan to resubmit, I would like to see these patches in 4.20. I just
got caught up in different project meanwhile.

P.