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Re: [PATCH v2] ppc/spapr: Add support for implement support for H_SCM_HE
From: |
David Gibson |
Subject: |
Re: [PATCH v2] ppc/spapr: Add support for implement support for H_SCM_HEALTH |
Date: |
Thu, 1 Apr 2021 13:26:11 +1100 |
On Thu, Apr 01, 2021 at 06:35:19AM +0530, Vaibhav Jain wrote:
> Add support for H_SCM_HEALTH hcall described at [1] for spapr
> nvdimms. This enables guest to detect the 'unarmed' status of a
> specific spapr nvdimm identified by its DRC and if its unarmed, mark
> the region backed by the nvdimm as read-only.
>
> The patch adds h_scm_health() to handle the H_SCM_HEALTH hcall which
> returns two 64-bit bitmaps (health bitmap, health bitmap mask) derived
> from 'struct nvdimm->unarmed' member.
>
> Linux kernel side changes to enable handling of 'unarmed' nvdimms for
> ppc64 are proposed at [2].
>
> References:
> [1] "Hypercall Op-codes (hcalls)"
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/powerpc/papr_hcalls.rst#n220
> [2] "powerpc/papr_scm: Mark nvdimm as unarmed if needed during probe"
>
> https://lore.kernel.org/linux-nvdimm/20210329113103.476760-1-vaibhav@linux.ibm.com/
>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
As well as the handful of comments below, this will definitely need to
wait for ppc-6.1 at this point.
> ---
> Changelog
>
> v2:
> * Added a check for drc->dev to ensure that the dimm is plugged in
> when servicing H_SCM_HEALTH. [ Shiva ]
> * Instead of accessing the 'nvdimm->unarmed' member directly use the
> object_property_get_bool accessor to fetch it. [ Shiva ]
> * Update the usage of PAPR_PMEM_UNARMED* macros [ Greg ]
> * Updated patch description reference#1 to point appropriate section
> in the documentation. [ Greg ]
> ---
> hw/ppc/spapr_nvdimm.c | 38 ++++++++++++++++++++++++++++++++++++++
> include/hw/ppc/spapr.h | 3 ++-
> 2 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c
> index b46c36917c..34096e4718 100644
> --- a/hw/ppc/spapr_nvdimm.c
> +++ b/hw/ppc/spapr_nvdimm.c
> @@ -31,6 +31,13 @@
> #include "qemu/range.h"
> #include "hw/ppc/spapr_numa.h"
>
> +/* DIMM health bitmap bitmap indicators. Taken from kernel's papr_scm.c */
> +/* SCM device is unable to persist memory contents */
> +#define PAPR_PMEM_UNARMED (1ULL << (63 - 0))
You can use PPC_BIT() for more clarity here.
> +/* Bits status indicators for health bitmap indicating unarmed dimm */
> +#define PAPR_PMEM_UNARMED_MASK (PAPR_PMEM_UNARMED)
I'm not sure why you want two equal #defines here.
> +
> bool spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
> uint64_t size, Error **errp)
> {
> @@ -467,6 +474,36 @@ static target_ulong h_scm_unbind_all(PowerPCCPU *cpu,
> SpaprMachineState *spapr,
> return H_SUCCESS;
> }
>
> +static target_ulong h_scm_health(PowerPCCPU *cpu, SpaprMachineState *spapr,
> + target_ulong opcode, target_ulong *args)
> +{
> + uint32_t drc_index = args[0];
> + SpaprDrc *drc = spapr_drc_by_index(drc_index);
> + NVDIMMDevice *nvdimm;
> +
> + if (drc && spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PMEM) {
This will fail badly if !drc (given index is way out of bounds). I'm
pretty sure you want
if (!drc || spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PMEM) {
> + return H_PARAMETER;
> + }
> +
> + /* Ensure that the dimm is plugged in */
> + if (!drc->dev) {
> + return H_HARDWARE;
H_HARDWARE doesn't seem right - it's the guest that has chosen to
attempt this on an unplugged LMB, not the (virtual) hardware's fault.
> + }
> +
> + nvdimm = NVDIMM(drc->dev);
> +
> + args[0] = 0;
> + /* Check if the nvdimm is unarmed and send its status via health bitmaps
> */
> + if (object_property_get_bool(OBJECT(nvdimm), NVDIMM_UNARMED_PROP, NULL))
> {
> + args[0] |= PAPR_PMEM_UNARMED;
> + }
> +
> + /* Update the health bitmap with the applicable mask */
> + args[1] = PAPR_PMEM_UNARMED_MASK;
> +
> + return H_SUCCESS;
> +}
> +
> static void spapr_scm_register_types(void)
> {
> /* qemu/scm specific hcalls */
> @@ -475,6 +512,7 @@ static void spapr_scm_register_types(void)
> spapr_register_hypercall(H_SCM_BIND_MEM, h_scm_bind_mem);
> spapr_register_hypercall(H_SCM_UNBIND_MEM, h_scm_unbind_mem);
> spapr_register_hypercall(H_SCM_UNBIND_ALL, h_scm_unbind_all);
> + spapr_register_hypercall(H_SCM_HEALTH, h_scm_health);
> }
>
> type_init(spapr_scm_register_types)
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 47cebaf3ac..6e1eafb05d 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -538,8 +538,9 @@ struct SpaprMachineState {
> #define H_SCM_BIND_MEM 0x3EC
> #define H_SCM_UNBIND_MEM 0x3F0
> #define H_SCM_UNBIND_ALL 0x3FC
> +#define H_SCM_HEALTH 0x400
>
> -#define MAX_HCALL_OPCODE H_SCM_UNBIND_ALL
> +#define MAX_HCALL_OPCODE H_SCM_HEALTH
>
> /* The hcalls above are standardized in PAPR and implemented by pHyp
> * as well.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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