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Re: [Xen-devel] [PATCH v2 5/7] x86: relocate pvh_info



On Mon, Jan 22, 2018 at 03:31:22AM -0700, Jan Beulich wrote:
> >>> On 19.01.18 at 17:39, <wei.liu2@xxxxxxxxxx> wrote:
> > On Fri, Jan 19, 2018 at 04:29:31PM +0000, Roger Pau Monné wrote:
> >> On Fri, Jan 19, 2018 at 03:34:56PM +0000, Wei Liu wrote:
> >> > diff --git a/xen/arch/x86/boot/build32.mk b/xen/arch/x86/boot/build32.mk
> >> > index 48c7407c00..028ac19b96 100644
> >> > --- a/xen/arch/x86/boot/build32.mk
> >> > +++ b/xen/arch/x86/boot/build32.mk
> >> > @@ -36,5 +36,8 @@ CFLAGS := $(filter-out -flto,$(CFLAGS))
> >> >  cmdline.o: cmdline.c $(CMDLINE_DEPS)
> >> >  
> >> >  reloc.o: reloc.c $(RELOC_DEPS)
> >> > +ifeq ($(CONFIG_PVH_GUEST),y)
> >> > +reloc.o: CFLAGS += -DCONFIG_PVH_GUEST
> >> > +endif
> >> 
> >> I would maybe do this above, where the rest of the CFLAGS are set.
> >> Certainly setting -DCONFIG_PVH_GUEST shouldn't cause issues elsewhere.
> >> 
> >> CFLAGS-$(CONFIG_PVH_GUEST) += -DCONFIG_PVH_GUEST
> >> CFLAGS += $(CFLAGS-y)
> >> 
> >> >  .PRECIOUS: %.bin %.lnk
> >> > diff --git a/xen/arch/x86/boot/defs.h b/xen/arch/x86/boot/defs.h
> >> > index 6abdc15446..05921a64a3 100644
> >> > --- a/xen/arch/x86/boot/defs.h
> >> > +++ b/xen/arch/x86/boot/defs.h
> >> > @@ -51,6 +51,9 @@ typedef unsigned short u16;
> >> >  typedef unsigned int u32;
> >> >  typedef unsigned long long u64;
> >> >  typedef unsigned int size_t;
> >> > +typedef u8 uint8_t;
> >> > +typedef u32 uint32_t;
> >> > +typedef u64 uint64_t;
> >> 
> >> This this seems to be always expanding, maybe better to simply replace
> >> the stdbool.h include above with types.h?
> >> 
> > 
> > I'm two minded here. My impression is that this wants to be minimal and
> > standalone. The content in types.h is a lot more than we need here.
> 
> Please keep it the (minimal) way you have it.
> 
> >> >  #define U16_MAX         ((u16)(~0U))
> >> >  #define UINT_MAX        (~0U)
> >> > diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> >> > index 0f652cea11..614e53081e 100644
> >> > --- a/xen/arch/x86/boot/head.S
> >> > +++ b/xen/arch/x86/boot/head.S
> >> > @@ -414,6 +414,7 @@ __pvh_start:
> >> >  
> >> >          /* Set trampoline_phys to use mfn 1 to avoid having a mapping 
> >> > at VA 0 */
> >> >          movw    $0x1000, sym_esi(trampoline_phys)
> >> > +        movl    $0x336ec578, %eax /* mov $XEN_HVM_START_MAGIC_VALUE, 
> >> > %eax */
> >> 
> >> Hm, if XEN_HVM_START_MAGIC_VALUE cannot be used I would rather prefer
> >> to use (%ebx).
> > 
> > The same reason I didn't include types.h + hvm_start_info.h here.
> > 
> > We can include both to make $XEN_HVM_START_MAGIC_VALUE work. But I think
> > using (%ebx) is better in here.
> 
> I agree (%ebx) is preferable.
> 

To avoid spamming the list with all the other acked patches, here is the
updated patch.

---8<---
From 1ac0afbbc0ecd620c5fba3a03bb084bc4dafc78e Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu2@xxxxxxxxxx>
Date: Wed, 17 Jan 2018 18:38:02 +0000
Subject: [PATCH] x86: relocate pvh_info
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Modify early boot code to relocate pvh info as well, so that we can be
sure __va in __start_xen works.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>

v2: use XEN_HVM_START_MAGIC_VALUE and switch statement in reloc.
Move header inclusion.

v3: Use (%ebx). Add blank lines.
---
 xen/arch/x86/boot/Makefile   |  7 ++++-
 xen/arch/x86/boot/build32.mk |  3 +++
 xen/arch/x86/boot/defs.h     |  3 +++
 xen/arch/x86/boot/head.S     | 25 ++++++++++--------
 xen/arch/x86/boot/reloc.c    | 62 +++++++++++++++++++++++++++++++++++++++-----
 5 files changed, 81 insertions(+), 19 deletions(-)

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index c6246c85d2..9fe5b309c5 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -7,10 +7,15 @@ CMDLINE_DEPS = $(DEFS_H_DEPS) video.h
 RELOC_DEPS = $(DEFS_H_DEPS) $(BASEDIR)/include/xen/multiboot.h \
             $(BASEDIR)/include/xen/multiboot2.h
 
+ifeq ($(CONFIG_PVH_GUEST),y)
+RELOC_DEPS += $(BASEDIR)/include/public/arch-x86/hvm/start_info.h
+RELOC_EXTRA = CONFIG_PVH_GUEST=y
+endif
+
 head.o: cmdline.S reloc.S
 
 cmdline.S: cmdline.c $(CMDLINE_DEPS)
        $(MAKE) -f build32.mk $@ CMDLINE_DEPS="$(CMDLINE_DEPS)"
 
 reloc.S: reloc.c $(RELOC_DEPS)
-       $(MAKE) -f build32.mk $@ RELOC_DEPS="$(RELOC_DEPS)"
+       $(MAKE) -f build32.mk $@ RELOC_DEPS="$(RELOC_DEPS)" $(RELOC_EXTRA)
diff --git a/xen/arch/x86/boot/build32.mk b/xen/arch/x86/boot/build32.mk
index 48c7407c00..028ac19b96 100644
--- a/xen/arch/x86/boot/build32.mk
+++ b/xen/arch/x86/boot/build32.mk
@@ -36,5 +36,8 @@ CFLAGS := $(filter-out -flto,$(CFLAGS))
 cmdline.o: cmdline.c $(CMDLINE_DEPS)
 
 reloc.o: reloc.c $(RELOC_DEPS)
+ifeq ($(CONFIG_PVH_GUEST),y)
+reloc.o: CFLAGS += -DCONFIG_PVH_GUEST
+endif
 
 .PRECIOUS: %.bin %.lnk
diff --git a/xen/arch/x86/boot/defs.h b/xen/arch/x86/boot/defs.h
index 6abdc15446..05921a64a3 100644
--- a/xen/arch/x86/boot/defs.h
+++ b/xen/arch/x86/boot/defs.h
@@ -51,6 +51,9 @@ typedef unsigned short u16;
 typedef unsigned int u32;
 typedef unsigned long long u64;
 typedef unsigned int size_t;
+typedef u8 uint8_t;
+typedef u32 uint32_t;
+typedef u64 uint64_t;
 
 #define U16_MAX                ((u16)(~0U))
 #define UINT_MAX       (~0U)
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 0f652cea11..aa2e2a93c8 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -414,6 +414,7 @@ __pvh_start:
 
         /* Set trampoline_phys to use mfn 1 to avoid having a mapping at VA 0 
*/
         movw    $0x1000, sym_esi(trampoline_phys)
+        movl    (%ebx), %eax /* mov $XEN_HVM_START_MAGIC_VALUE, %eax */
         jmp     trampoline_setup
 
 #endif /* CONFIG_PVH_GUEST */
@@ -578,18 +579,20 @@ trampoline_setup:
         /* Get bottom-most low-memory stack address. */
         add     $TRAMPOLINE_SPACE,%ecx
 
-#ifdef CONFIG_PVH_GUEST
-        cmpb    $0, sym_fs(pvh_boot)
-        jne     1f
-#endif
-
-        /* Save the Multiboot info struct (after relocation) for later use. */
+        /* Save Multiboot / PVH info struct (after relocation) for later use. 
*/
         push    %ecx                /* Bottom-most low-memory stack address. */
-        push    %ebx                /* Multiboot information address. */
-        push    %eax                /* Multiboot magic. */
+        push    %ebx                /* Multiboot / PVH information address. */
+        push    %eax                /* Magic number. */
         call    reloc
-        mov     %eax,sym_fs(multiboot_ptr)
+#ifdef CONFIG_PVH_GUEST
+        cmp     $0,sym_fs(pvh_boot)
+        je      1f
+        mov     %eax,sym_fs(pvh_start_info_pa)
+        jmp     2f
+#endif
 1:
+        mov     %eax,sym_fs(multiboot_ptr)
+2:
 
         /*
          * Now trampoline_phys points to the following structure (lowest 
address
@@ -598,12 +601,12 @@ trampoline_setup:
          * +------------------------+
          * | TRAMPOLINE_STACK_SPACE |
          * +------------------------+
-         * |        mbi data        |
+         * |     Data (MBI / PVH)   |
          * +- - - - - - - - - - - - +
          * |    TRAMPOLINE_SPACE    |
          * +------------------------+
          *
-         * mbi data grows downwards from the highest address of 
TRAMPOLINE_SPACE
+         * Data grows downwards from the highest address of TRAMPOLINE_SPACE
          * region to the end of the trampoline. The rest of TRAMPOLINE_SPACE is
          * reserved for trampoline code and data.
          */
diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
index b992678b5e..216edb83a6 100644
--- a/xen/arch/x86/boot/reloc.c
+++ b/xen/arch/x86/boot/reloc.c
@@ -14,8 +14,8 @@
 
 /*
  * This entry point is entered from xen/arch/x86/boot/head.S with:
- *   - 0x4(%esp) = MULTIBOOT_MAGIC,
- *   - 0x8(%esp) = MULTIBOOT_INFORMATION_ADDRESS,
+ *   - 0x4(%esp) = MAGIC,
+ *   - 0x8(%esp) = INFORMATION_ADDRESS,
  *   - 0xc(%esp) = TOPMOST_LOW_MEMORY_STACK_ADDRESS.
  */
 asm (
@@ -71,6 +71,41 @@ static u32 copy_string(u32 src)
     return copy_mem(src, p - src + 1);
 }
 
+#ifdef CONFIG_PVH_GUEST
+
+#include <public/arch-x86/hvm/start_info.h>
+
+static struct hvm_start_info *pvh_info_reloc(u32 in)
+{
+    struct hvm_start_info *out;
+
+    out = _p(copy_mem(in, sizeof(*out)));
+
+    if ( out->cmdline_paddr )
+        out->cmdline_paddr = copy_string(out->cmdline_paddr);
+
+    if ( out->nr_modules )
+    {
+        unsigned int i;
+        struct hvm_modlist_entry *mods;
+
+        out->modlist_paddr =
+            copy_mem(out->modlist_paddr,
+                     out->nr_modules * sizeof(struct hvm_modlist_entry));
+
+        mods = _p(out->modlist_paddr);
+
+        for ( i = 0; i < out->nr_modules; i++ )
+        {
+            if ( mods[i].cmdline_paddr )
+                mods[i].cmdline_paddr = copy_string(mods[i].cmdline_paddr);
+        }
+    }
+
+    return out;
+}
+#endif
+
 static multiboot_info_t *mbi_reloc(u32 mbi_in)
 {
     int i;
@@ -226,14 +261,27 @@ static multiboot_info_t *mbi2_reloc(u32 mbi_in)
     return mbi_out;
 }
 
-multiboot_info_t __stdcall *reloc(u32 mb_magic, u32 mbi_in, u32 trampoline)
+void __stdcall *reloc(u32 magic, u32 in, u32 trampoline)
 {
     alloc = trampoline;
 
-    if ( mb_magic == MULTIBOOT2_BOOTLOADER_MAGIC )
-        return mbi2_reloc(mbi_in);
-    else
-        return mbi_reloc(mbi_in);
+    switch ( magic )
+    {
+    case MULTIBOOT_BOOTLOADER_MAGIC:
+        return mbi_reloc(in);
+
+    case MULTIBOOT2_BOOTLOADER_MAGIC:
+        return mbi2_reloc(in);
+
+#ifdef CONFIG_PVH_GUEST
+    case XEN_HVM_START_MAGIC_VALUE:
+        return pvh_info_reloc(in);
+#endif
+
+    default:
+        /* Nothing we can do */
+        return NULL;
+    }
 }
 
 /*
-- 
2.11.0


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