Subject: Re: [RFC PATCH 12/12] virt/acpi: add SDEI table if SDEI is enabled

From: Igor Mammedov <[email-masked]>
Date: Thu, 10 Oct 2019 15:57:23 +0200

On Thu, 10 Oct 2019 21:08:10 +0800
Guoheyi <[email-masked]> wrote:

> Thanks for your comments.
> 
> On 2019/10/10 17:15, Igor Mammedov wrote:
> > On Tue, 24 Sep 2019 23:21:51 +0800
> > Heyi Guo <[email-masked]> wrote:
> >  
> >> Add SDEI table if SDEI is enabled, so that guest OS can get aware and
> >> utilize the interfaces.
> >>
> >> Signed-off-by: Heyi Guo <[email-masked]>
> >> Cc: Peter Maydell <[email-masked]>
> >> Cc: Dave Martin <[email-masked]>
> >> Cc: Marc Zyngier <[email-masked]>
> >> Cc: Mark Rutland <[email-masked]>
> >> Cc: James Morse <[email-masked]>
> >> Cc: Shannon Zhao <[email-masked]>
> >> Cc: "Michael S. Tsirkin" <[email-masked]>
> >> Cc: Igor Mammedov <[email-masked]>
> >> ---
> >>   hw/arm/virt-acpi-build.c    | 16 ++++++++++++++++
> >>   include/hw/acpi/acpi-defs.h |  5 +++++
> >>   2 files changed, 21 insertions(+)
> >>
> >> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> >> index 6cdf156..1088214 100644
> >> --- a/hw/arm/virt-acpi-build.c
> >> +++ b/hw/arm/virt-acpi-build.c
> >> @@ -32,6 +32,7 @@
> >>   #include "trace.h"
> >>   #include "hw/core/cpu.h"
> >>   #include "target/arm/cpu.h"
> >> +#include "target/arm/sdei.h"
> >>   #include "hw/acpi/acpi-defs.h"
> >>   #include "hw/acpi/acpi.h"
> >>   #include "hw/nvram/fw_cfg.h"
> >> @@ -475,6 +476,16 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> >>   }
> >>     
> > here should be a comment describing purpose with a reference to spec  
> OK.
> 
> >  
> >>   static void
> >> +build_sdei(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> >> +{
> >> +    int sdei_start = table_data->len;
> >> +
> >> +    (void)acpi_data_push(table_data, sizeof(AcpiSdei));
> >> +    build_header(linker, table_data, (void *)(table_data->data + sdei_start),
> >> +                 "SDEI", table_data->len - sdei_start, 1, NULL, NULL);
> >> +}  
> > that's dummy table and doesn't match what spec describes,
> > It doesn't look correct SDEI table.  
> 
> Refer to below document, Appendix C, I see the definition of SDEI is 
> really a dummy table, also it is said in the document: The table 
> consists only of a basic header with revision 1.
> 
> http://infocenter.arm.com/help/topic/com.arm.doc.den0054a/ARM_DEN0054A_Software_Delegated_Exception_Interface.pdf
> 
> Do I miss anything?
No you are right and I was mistaken.
It's pretty waste-full way to communicate to OS a Boolean flag
that a new GHEST event is supported. But since they managed to make
it a spec, it should be coded as such.

> 
> >  
> >> +
> >> +static void
> >>   build_spcr(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> >>   {
> >>       AcpiSerialPortConsoleRedirection *spcr;
> >> @@ -796,6 +807,11 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
> >>       acpi_add_table(table_offsets, tables_blob);
> >>       build_spcr(tables_blob, tables->linker, vms);
> >>   
> >> +    if (sdei_enabled) {
> >> +        acpi_add_table(table_offsets, tables_blob);
> >> +        build_sdei(tables_blob, tables->linker, vms);
> >> +    }
> >> +
> >>       if (ms->numa_state->num_nodes > 0) {
> >>           acpi_add_table(table_offsets, tables_blob);
> >>           build_srat(tables_blob, tables->linker, vms);
> >> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> >> index 57a3f58..0a2265d 100644
> >> --- a/include/hw/acpi/acpi-defs.h
> >> +++ b/include/hw/acpi/acpi-defs.h
> >> @@ -634,4 +634,9 @@ struct AcpiIortRC {
> >>   } QEMU_PACKED;
> >>   typedef struct AcpiIortRC AcpiIortRC;
> >>   
> >> +struct AcpiSdei {
> >> +    ACPI_TABLE_HEADER_DEF     /* ACPI common table header */
> >> +} QEMU_PACKED;
> >> +typedef struct AcpiSdei AcpiSdei;  
> > we don't use packed structures for ACPI anymore, see build_rsdp() for
> > example of how tables are composed and comment style required for each field.  
> Sure; will fix it in v2.
> 
> Thanks,
> 
> Heyi
> 
> >  
> >>   #endif  
> >
> > .
> >  
> 
> 

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