Re: [Qemu-devel] [PATCH 8/9] nvdimm acpi: emulate dsm method

[Xiao Guangrong]

On 03/02/2016 01:12 AM, Michael S. Tsirkin wrote:
> On Tue, Mar 01, 2016 at 06:56:10PM +0800, Xiao Guangrong wrote:
> > Emulate dsm method after IO VM-exit
> >
> > Currently, we only introduce the framework and no function is actually
> > supported
> >
> > Signed-off-by: Xiao Guangrong <address@hidden>
> > ---
> >   hw/acpi/aml-build.c         |  2 +-
> >   hw/acpi/nvdimm.c            | 44 ++++++++++++++++++++++++++++++++++++++++++++
> >   include/hw/acpi/aml-build.h |  1 +
> >   include/hw/mem/nvdimm.h     |  8 ++++++++
> >   4 files changed, 54 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> > index ab89ca6..da11bf8 100644
> > --- a/hw/acpi/aml-build.c
> > +++ b/hw/acpi/aml-build.c
> > @@ -227,7 +227,7 @@ static void build_extop_package(GArray *package, uint8_t op)
> >       build_prepend_byte(package, 0x5B); /* ExtOpPrefix */
> >   }
> >
> > -static void build_append_int_noprefix(GArray *table, uint64_t value, int size)
> > +void build_append_int_noprefix(GArray *table, uint64_t value, int size)
> >   {
> >       int i;
> >
> > diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> > index 781f6c1..e0b483a 100644
> > --- a/hw/acpi/nvdimm.c
> > +++ b/hw/acpi/nvdimm.c
> > @@ -393,12 +393,56 @@ typedef struct NvdimmDsmOut NvdimmDsmOut;
> >   static uint64_t
> >   nvdimm_dsm_read(void *opaque, hwaddr addr, unsigned size)
> >   {
> > +    fprintf(stderr, "BUG: we never read _DSM IO Port.\n");
> >       return 0;
> >   }
> >
> >   static void
> >   nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
> >   {
> > +    NvdimmDsmIn *in;
> > +    GArray *out;
> > +    uint32_t buf_size;
> > +    hwaddr dsm_mem_addr = val;
> > +
> > +    nvdimm_debug("dsm memory address %#lx.\n", dsm_mem_addr);
> > +
> > +    /*
> > +     * The DSM memory is mapped to guest address space so an evil guest
> > +     * can change its content while we are doing DSM emulation. Avoid
> > +     * this by copying DSM memory to QEMU local memory.
> > +     */
> > +    in = g_malloc(TARGET_PAGE_SIZE);
> > +    cpu_physical_memory_read(dsm_mem_addr, in, TARGET_PAGE_SIZE);
> > +
> > +    le32_to_cpus(&in->revision);
> > +    le32_to_cpus(&in->function);
> > +    le32_to_cpus(&in->handle);
> > +
> > +    nvdimm_debug("Revision %#x Handler %#x Function %#x.\n", in->revision,
> > +                 in->handle, in->function);
> > +
> > +    out = g_array_new(false, true /* clear */, 1);
> > +
> > +    /*
> > +     * function 0 is called to inquire what functions are supported by
> > +     * OSPM
> > +     */
> > +    if (in->function == 0) {
> > +        build_append_int_noprefix(out, 0 /* No function Supported */,
> > +                                  sizeof(uint8_t));
> > +    } else {
> > +        /* No function is supported yet. */
> > +        build_append_int_noprefix(out, 1 /* Not Supported */,
> > +                                  sizeof(uint8_t));
> > +    }
> > +
> > +    buf_size = cpu_to_le32(out->len);
> > +    cpu_physical_memory_write(dsm_mem_addr, &buf_size, sizeof(buf_size));
> > +    cpu_physical_memory_write(dsm_mem_addr + sizeof(buf_size), out->data,
> > +                              out->len);
>
> BTW, how do we know buffer is big enough? Add assert here?

I planed to do it when we introduce the real handler of NVDIMM command, but yes,
it is better doing it in this patchset. Will follow it in the next version.

> Also, you have a packed structure with the layout, correct?
> Can't you use that instead of open-coding it?


Okay, how about do it like this:

diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
index a6359cc..2812f7a 100644
--- a/hw/acpi/nvdimm.c
+++ b/hw/acpi/nvdimm.c
@@ -401,7 +401,7 @@ static void
 nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
 {
     NvdimmDsmIn *in;
-    GArray *out;
+    NvdimmDsmOut *out;
     uint32_t buf_size;
     hwaddr dsm_mem_addr = val;

@@ -422,27 +422,33 @@ nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, 
unsigned size)
     nvdimm_debug("Revision %#x Handler %#x Function %#x.\n", in->revision,
                  in->handle, in->function);

-    out = g_array_new(false, true /* clear */, 1);
+    out = g_malloc(TARGET_PAGE_SIZE);
+
+    out->len = sizeof(out);

     /*
      * function 0 is called to inquire what functions are supported by
      * OSPM
      */
     if (in->function == 0) {
-        build_append_int_noprefix(out, 0 /* No function Supported */,
-                                  sizeof(uint8_t));
+        /* No function Supported */
+        uint32_t cmd_list = cpu_to_le32(0);
+
+        out->len += sizeof(cmd_list);
     } else {
-        /* No function is supported yet. */
-        build_append_int_noprefix(out, 1 /* Not Supported */,
-                                  sizeof(uint8_t));
+        /* Not Supported */
+        uint32_t status =  cpu_to_le32(1);
+
+        out->len = sizeof(status);
     }

-    buf_size = cpu_to_le32(out->len);
-    cpu_physical_memory_write(dsm_mem_addr, &buf_size, sizeof(buf_size));
-    cpu_physical_memory_write(dsm_mem_addr + sizeof(buf_size), out->data,
-                              out->len);
+    buf_size = out->len;
+    assert(buf_size <= TARGET_PAGE_SIZE);
+
+    out->len = cpu_to_le32(out->len);
+    cpu_physical_memory_write(dsm_mem_addr, out, buf_size);
     g_free(in);
-    g_array_free(out, true);
+    g_free(out);
 }

 static const MemoryRegionOps nvdimm_dsm_ops = {