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

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Mar 02, 2016 at 12:00:42PM +0800, Xiao Guangrong wrote:
> 
> 
> 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 <guangrong.xiao@linux.intel.com>
> >>---
> >>  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 = {

Not really much better. I suggested a better version in
another thread.