On Fri, Sep 05, 2025 at 05:09:23PM +0200, Mauro Carvalho Chehab wrote: > While the HEST layout didn't change, there are some internal > changes related to how offsets are calculated and how memory error > events are triggered. > > Update specs to reflect such changes. > > Signed-off-by: Mauro Carvalho Chehab <[email protected]> > Reviewed-by: Jonathan Cameron <[email protected]> > Reviewed-by: Igor Mammedov <[email protected]> > --- > docs/specs/acpi_hest_ghes.rst | 28 +++++++++++++++++----------- > 1 file changed, 17 insertions(+), 11 deletions(-) > > diff --git a/docs/specs/acpi_hest_ghes.rst b/docs/specs/acpi_hest_ghes.rst > index c3e9f8d9a702..3d1b85d74b70 100644 > --- a/docs/specs/acpi_hest_ghes.rst > +++ b/docs/specs/acpi_hest_ghes.rst > @@ -89,12 +89,21 @@ Design Details > addresses in the "error_block_address" fields with a pointer to the > respective "Error Status Data Block" in the "etc/hardware_errors" blob. > > -(8) QEMU defines a third and write-only fw_cfg blob which is called > - "etc/hardware_errors_addr". Through that blob, the firmware can send back > - the guest-side allocation addresses to QEMU. The > "etc/hardware_errors_addr" > - blob contains a 8-byte entry. QEMU generates a single WRITE_POINTER > command > - for the firmware. The firmware will write back the start address of > - "etc/hardware_errors" blob to the fw_cfg file "etc/hardware_errors_addr". > +(8) QEMU defines a third and write-only fw_cfg blob to store the location > + where the error block offsets, read ack registers and CPER records are > + stored. > + > + Up to QEMU 9.2, the location was at "etc/hardware_errors_addr", and > + contains a GPA for the beginning of "etc/hardware_errors". > + > + Newer versions place the location at "etc/acpi_table_hest_addr", > + pointing to the GPA of the HEST table. > + > + Using above mentioned 'fw_cfg' files, the firmware can send back the > + guest-side allocation addresses to QEMU. They contain a 8-byte entry. > + QEMU generates a single WRITE_POINTER command for the firmware. The > + firmware will write back the start address of either > "etc/hardware_errors" > + or HEST table at the corresponding fw_cfg file. > > (9) When QEMU gets a SIGBUS from the kernel, QEMU writes CPER into > corresponding > "Error Status Data Block", guest memory, and then injects platform > specific > @@ -105,8 +114,5 @@ Design Details > kernel, on receiving notification, guest APEI driver could read the > CPER error > and take appropriate action. > > -(11) kvm_arch_on_sigbus_vcpu() uses source_id as index in > "etc/hardware_errors" to > - find out "Error Status Data Block" entry corresponding to error source. > So supported > - source_id values should be assigned here and not be changed afterwards > to make sure > - that guest will write error into expected "Error Status Data Block" > even if guest was > - migrated to a newer QEMU. > +(11) kvm_arch_on_sigbus_vcpu() report RAS errors via a SEA notifications,
reports > + when a SIGBUS event is triggered. > -- > 2.51.0
