[PATCH kvmtool 0/1] riscv: Add zihintpause extension support

[PATCH kvmtool 0/1] riscv: Add zihintpause extension support

[Mayuresh Chitale]

This patch exports the zihintpause extension to the guest if it is
available on the host. It depends on the following tree from Anup:

https://github.com/avpatel/kvmtool/tree/riscv_svpbmt_sstc_v1

Mayuresh Chitale (1):
  riscv: Add zihintpause extension support

 riscv/fdt.c             | 2 ++
 riscv/include/asm/kvm.h | 1 +
 2 files changed, 3 insertions(+)

-- 
2.34.1

[PATCH kvmtool 1/1] riscv: Add zihintpause extension support

[Mayuresh Chitale]

The zihintpause extension allows software to use the PAUSE instruction to
reduce energy consumption while executing spin-wait code sequences. Add the
zihintpause extension to the device tree if it is supported by the host.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
---
 riscv/fdt.c             | 2 ++
 riscv/include/asm/kvm.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/riscv/fdt.c b/riscv/fdt.c
index e3d7717..7997edc 100644
--- a/riscv/fdt.c
+++ b/riscv/fdt.c
@@ -19,6 +19,8 @@ struct isa_ext_info {
 struct isa_ext_info isa_info_arr[] = {
 	{"svpbmt", KVM_RISCV_ISA_EXT_SVPBMT},
 	{"sstc", KVM_RISCV_ISA_EXT_SSTC},
+	{"Zihintpause", KVM_RISCV_ISA_EXT_ZIHINTPAUSE},
+
 };
 
 static void dump_fdt(const char *dtb_file, void *fdt)
diff --git a/riscv/include/asm/kvm.h b/riscv/include/asm/kvm.h
index 7351417..f6f7963 100644
--- a/riscv/include/asm/kvm.h
+++ b/riscv/include/asm/kvm.h
@@ -98,6 +98,7 @@ enum KVM_RISCV_ISA_EXT_ID {
 	KVM_RISCV_ISA_EXT_M,
 	KVM_RISCV_ISA_EXT_SVPBMT,
 	KVM_RISCV_ISA_EXT_SSTC,
+	KVM_RISCV_ISA_EXT_ZIHINTPAUSE,
 	KVM_RISCV_ISA_EXT_MAX,
 };
 
-- 
2.34.1

Re: [PATCH kvmtool 1/1] riscv: Add zihintpause extension support

[Andrew Jones]

On Fri, Sep 16, 2022 at 12:13:24PM +0530, Mayuresh Chitale wrote:
> The zihintpause extension allows software to use the PAUSE instruction to
> reduce energy consumption while executing spin-wait code sequences. Add the
> zihintpause extension to the device tree if it is supported by the host.
> 
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
> ---
>  riscv/fdt.c             | 2 ++
>  riscv/include/asm/kvm.h | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/riscv/fdt.c b/riscv/fdt.c
> index e3d7717..7997edc 100644
> --- a/riscv/fdt.c
> +++ b/riscv/fdt.c
> @@ -19,6 +19,8 @@ struct isa_ext_info {
>  struct isa_ext_info isa_info_arr[] = {
>  	{"svpbmt", KVM_RISCV_ISA_EXT_SVPBMT},
>  	{"sstc", KVM_RISCV_ISA_EXT_SSTC},
> +	{"Zihintpause", KVM_RISCV_ISA_EXT_ZIHINTPAUSE},

We don't capitalize the first S in 'Sstc' above, so I don't think we want
to capitalize this Z either.

> +

extra blank line

>  };
>  
>  static void dump_fdt(const char *dtb_file, void *fdt)
> diff --git a/riscv/include/asm/kvm.h b/riscv/include/asm/kvm.h
> index 7351417..f6f7963 100644
> --- a/riscv/include/asm/kvm.h
> +++ b/riscv/include/asm/kvm.h
> @@ -98,6 +98,7 @@ enum KVM_RISCV_ISA_EXT_ID {
>  	KVM_RISCV_ISA_EXT_M,
>  	KVM_RISCV_ISA_EXT_SVPBMT,
>  	KVM_RISCV_ISA_EXT_SSTC,
> +	KVM_RISCV_ISA_EXT_ZIHINTPAUSE,

This should be updated with a uapi header update using
util/update_headers.sh


>  	KVM_RISCV_ISA_EXT_MAX,
>  };
>  
> -- 
> 2.34.1
>

Thanks,
drew