On Wed, Mar 4, 2020 at 7:50 PM Pingfan Liu <kernelfans@xxxxxxxxx> wrote:
>
> At present, plpar_hcall(H_SCM_BIND_MEM, ...) takes a very long time, so
> if dumping to fsdax, it will take a very long time.
>
> Take a closer look, during the papr_scm initialization, the only
> configuration is through drc_pmem_bind()-> plpar_hcall(H_SCM_BIND_MEM,
> ...), which helps to set up the bound address.
>
> On pseries, for kexec -l/-p kernel, there is no reset of hardware, and this
> step can be stepped around to save times. So the pmem bound address can be
> passed to the 2nd kernel through a dynamic added property "bound-addr" in
> dt node 'ibm,pmemory'.
>
> Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
> To: linuxppc-dev@xxxxxxxxxxxxxxxx
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Hari Bathini <hbathini@xxxxxxxxxxxxx>
> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> Cc: Oliver O'Halloran <oohall@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Andrew Donnellan <ajd@xxxxxxxxxxxxx>
> Cc: Christophe Leroy <christophe.leroy@xxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Frank Rowand <frowand.list@xxxxxxxxx>
> Cc: kexec@xxxxxxxxxxxxxxxxxxx
> ---
> note: This patch has not been tested since I can not get such a pseries with pmem.
> Please kindly to give some suggestion, thanks.
There was some qemu patches to implement the Hcall interface floating
around a while ago. I'm not sure they ever made it into upstream qemu
though.
> ---
> arch/powerpc/platforms/pseries/of_helpers.c | 1 +
> arch/powerpc/platforms/pseries/papr_scm.c | 33 ++++++++++++++++++++---------
> drivers/of/base.c | 1 +
> 3 files changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/of_helpers.c b/arch/powerpc/platforms/pseries/of_helpers.c
> index 1022e0f..2c7bab4 100644
> --- a/arch/powerpc/platforms/pseries/of_helpers.c
> +++ b/arch/powerpc/platforms/pseries/of_helpers.c
> @@ -34,6 +34,7 @@ struct property *new_property(const char *name, const int length,
> kfree(new);
> return NULL;
> }
> +EXPORT_SYMBOL(new_property);
>
> /**
> * pseries_of_derive_parent - basically like dirname(1)
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index 0b4467e..54ae903 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -14,6 +14,7 @@
> #include <linux/delay.h>
>
> #include <asm/plpar_wrappers.h>
> +#include "of_helpers.h"
>
> #define BIND_ANY_ADDR (~0ul)
>
> @@ -383,7 +384,7 @@ static int papr_scm_probe(struct platform_device *pdev)
> {
> struct device_node *dn = pdev->dev.of_node;
> u32 drc_index, metadata_size;
> - u64 blocks, block_size;
> + u64 blocks, block_size, bound_addr = 0;
> struct papr_scm_priv *p;
> const char *uuid_str;
> u64 uuid[2];
> @@ -440,17 +441,29 @@ static int papr_scm_probe(struct platform_device *pdev)
> p->metadata_size = metadata_size;
> p->pdev = pdev;
>
> - /* request the hypervisor to bind this region to somewhere in memory */
> - rc = drc_pmem_bind(p);
> + of_property_read_u64(dn, "bound-addr", &bound_addr);
> + if (bound_addr) {
> + p->bound_addr = bound_addr;
> + } else {
> + struct property *property;
> + u64 big;
>
> - /* If phyp says drc memory still bound then force unbound and retry */
> - if (rc == H_OVERLAP)
> - rc = drc_pmem_query_n_bind(p);
> + /* request the hypervisor to bind this region to somewhere in memory */
> + rc = drc_pmem_bind(p);
>
> - if (rc != H_SUCCESS) {
> - dev_err(&p->pdev->dev, "bind err: %d\n", rc);
> - rc = -ENXIO;
> - goto err;
> + /* If phyp says drc memory still bound then force unbound and retry */
> + if (rc == H_OVERLAP)
> + rc = drc_pmem_query_n_bind(p);
> +
> + if (rc != H_SUCCESS) {
> + dev_err(&p->pdev->dev, "bind err: %d\n", rc);
> + rc = -ENXIO;
> + goto err;
> + }
> + big = cpu_to_be64(p->bound_addr);
> + property = new_property("bound-addr", sizeof(u64), (const unsigned char *)&big,
> + NULL);
That should probably be "linux,bound-addr"
The other thing that stands out to me is that you aren't removing the
property when the region is unbound. As a general rule I'd prefer we
didn't hack the DT at runtime, but if we are going to then we should
make sure we're not putting anything wrong in there.
> + of_add_property(dn, property);
> }
>
> /* setup the resource for the newly bound range */
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index ae03b12..602d2a9 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1817,6 +1817,7 @@ int of_add_property(struct device_node *np, struct property *prop)
>
> return rc;
> }
> +EXPORT_SYMBOL_GPL(of_add_property);
>
> int __of_remove_property(struct device_node *np, struct property *prop)
> {
> --
> 2.7.5
>
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