On Tue, May 16, 2023 at 03:11:49PM -0700, Stefano Stabellini wrote:
> On Tue, 16 May 2023, Roger Pau Monné wrote:
> > On Tue, May 16, 2023 at 10:10:07AM +0200, Roger Pau Monné wrote:
> > > On Mon, May 15, 2023 at 05:16:27PM -0700, Stefano Stabellini wrote:
> > > > On Mon, 15 May 2023, Jan Beulich wrote:
> > > > > On 15.05.2023 10:48, Roger Pau Monné wrote:
> > > > > > On Fri, May 12, 2023 at 06:17:19PM -0700, Stefano Stabellini wrote:
> > > > > >> From: Stefano Stabellini <stefano.stabell...@amd.com>
> > > > > >>
> > > > > >> Xen always generates a XSDT table even if the firmware provided a
> > > > > >> RSDT
> > > > > >> table. Instead of copying the XSDT header from the firmware table
> > > > > >> (that
> > > > > >> might be missing), generate the XSDT header from a preset.
> > > > > >>
> > > > > >> Signed-off-by: Stefano Stabellini <stefano.stabell...@amd.com>
> > > > > >> ---
> > > > > >> xen/arch/x86/hvm/dom0_build.c | 32
> > > > > >> +++++++++-----------------------
> > > > > >> 1 file changed, 9 insertions(+), 23 deletions(-)
> > > > > >>
> > > > > >> diff --git a/xen/arch/x86/hvm/dom0_build.c
> > > > > >> b/xen/arch/x86/hvm/dom0_build.c
> > > > > >> index 307edc6a8c..5fde769863 100644
> > > > > >> --- a/xen/arch/x86/hvm/dom0_build.c
> > > > > >> +++ b/xen/arch/x86/hvm/dom0_build.c
> > > > > >> @@ -963,13 +963,18 @@ static int __init pvh_setup_acpi_xsdt(struct
> > > > > >> domain *d, paddr_t madt_addr,
> > > > > >> paddr_t *addr)
> > > > > >> {
> > > > > >> struct acpi_table_xsdt *xsdt;
> > > > > >> - struct acpi_table_header *table;
> > > > > >> - struct acpi_table_rsdp *rsdp;
> > > > > >> const struct acpi_table_desc *tables =
> > > > > >> acpi_gbl_root_table_list.tables;
> > > > > >> unsigned long size = sizeof(*xsdt);
> > > > > >> unsigned int i, j, num_tables = 0;
> > > > > >> - paddr_t xsdt_paddr;
> > > > > >> int rc;
> > > > > >> + struct acpi_table_header header = {
> > > > > >> + .signature = "XSDT",
> > > > > >> + .length = sizeof(struct acpi_table_header),
> > > > > >> + .revision = 0x1,
> > > > > >> + .oem_id = "Xen",
> > > > > >> + .oem_table_id = "HVM",
> > > > > >
> > > > > > I think this is wrong, as according to the spec the OEM Table ID
> > > > > > must
> > > > > > match the OEM Table ID in the FADT.
> > > > > >
> > > > > > We likely want to copy the OEM ID and OEM Table ID from the RSDP,
> > > > > > and
> > > > > > possibly also the other OEM related fields.
> > > > > >
> > > > > > Alternatively we might want to copy and use the RSDT on systems that
> > > > > > lack an XSDT, or even just copy the header from the RSDT into Xen's
> > > > > > crafted XSDT, since the format of the RSDP and the XSDT headers are
> > > > > > exactly the same (the difference is in the size of the description
> > > > > > headers that come after).
> > > > >
> > > > > I guess I'd prefer that last variant.
> > > >
> > > > I tried this approach (together with the second patch for necessity) and
> > > > it worked.
> > > >
> > > > diff --git a/xen/arch/x86/hvm/dom0_build.c
> > > > b/xen/arch/x86/hvm/dom0_build.c
> > > > index fd2cbf68bc..11d6d1bc23 100644
> > > > --- a/xen/arch/x86/hvm/dom0_build.c
> > > > +++ b/xen/arch/x86/hvm/dom0_build.c
> > > > @@ -967,6 +967,10 @@ static int __init pvh_setup_acpi_xsdt(struct
> > > > domain *d, paddr_t madt_addr,
> > > > goto out;
> > > > }
> > > > xsdt_paddr = rsdp->xsdt_physical_address;
> > > > + if ( !xsdt_paddr )
> > > > + {
> > > > + xsdt_paddr = rsdp->rsdt_physical_address;
> > > > + }
> > > > acpi_os_unmap_memory(rsdp, sizeof(*rsdp));
> > > > table = acpi_os_map_memory(xsdt_paddr, sizeof(*table));
> > > > if ( !table )
> > >
> > > To be slightly more consistent, could you use:
> > >
> > > /*
> > > * Note the header is the same for both RSDT and XSDT, so it's fine to
> > > * copy the native RSDT header to the Xen crafted XSDT if no native
> > > * XSDT is available.
> > > */
> > > if (rsdp->revision > 1 && rsdp->xsdt_physical_address)
> > > sdt_paddr = rsdp->xsdt_physical_address;
> > > else
> > > sdt_paddr = rsdp->rsdt_physical_address;
> > >
> > > It was an oversight of mine to not check for the RSDP revision, as
> > > RSDP < 2 will never have an XSDT. Also add:
> > >
> > > Fixes: 1d74282c455f ('x86: setup PVHv2 Dom0 ACPI tables')
> >
> > Just realized this will require some more work so that the guest
> > (dom0) provided RSDP is at least revision 2. You will need to adjust
> > the field and recalculate the checksum if needed.
>
> But we are always providing RSDP version 2 in pvh_setup_acpi, right?
Yes, as said in the reply to Jan, just ignore this.
Thanks, Roger.
