[v2] xen/riscv: introduce p2m functionality

[PATCH v2 02/17] xen/riscv: introduce sbi_remote_hfence_gvma_vmid()

Posted by Oleksii Kurochko 4 months, 3 weeks ago

It instructs the remote harts to execute one or more HFENCE.GVMA instructions
by making an SBI call, covering the range of guest physical addresses between
start_addr and start_addr + size only for the given VMID.

This function call is only valid for harts implementing hypervisor extension.

The remote fence operation applies to the entire address space if either:
  - start_addr and size are both 0, or
  - size is equal to 2^XLEN-1.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in V2:
 - New patch.
---
 xen/arch/riscv/include/asm/sbi.h | 17 +++++++++++++++++
 xen/arch/riscv/sbi.c             |  9 +++++++++
 2 files changed, 26 insertions(+)

diff --git a/xen/arch/riscv/include/asm/sbi.h b/xen/arch/riscv/include/asm/sbi.h
index 8e346347af..2644833eb4 100644
--- a/xen/arch/riscv/include/asm/sbi.h
+++ b/xen/arch/riscv/include/asm/sbi.h
@@ -110,6 +110,23 @@ int sbi_remote_sfence_vma(const cpumask_t *cpu_mask, vaddr_t start,
 int sbi_remote_hfence_gvma(const cpumask_t *cpu_mask, vaddr_t start,
                            size_t size);
 
+/*
+ * Instruct the remote harts to execute one or more HFENCE.GVMA instructions,
+ * covering the range of guest physical addresses between start_addr and
+ * start_addr + size only for the given VMID. This function call is only
+ * valid for harts implementing hypervisor extension.
+ * The remote fence operation applies to the entire address space if either:
+ *  - start_addr and size are both 0, or
+ *  - size is equal to 2^XLEN-1.
+ *
+ * @cpu_mask a cpu mask containing all the target CPUs (in Xen space).
+ * @param start virtual address start
+ * @param size virtual address range size
+ * @param vmid virtual machine id
+ */
+int sbi_remote_hfence_gvma_vmid(const cpumask_t *cpu_mask, vaddr_t start,
+                                size_t size, unsigned long vmid);
+
 /*
  * Initialize SBI library
  *
diff --git a/xen/arch/riscv/sbi.c b/xen/arch/riscv/sbi.c
index 0613ad1cb0..bfd1193509 100644
--- a/xen/arch/riscv/sbi.c
+++ b/xen/arch/riscv/sbi.c
@@ -267,6 +267,15 @@ int sbi_remote_hfence_gvma(const cpumask_t *cpu_mask, vaddr_t start,
                       cpu_mask, start, size, 0, 0);
 }
 
+int sbi_remote_hfence_gvma_vmid(const cpumask_t *cpu_mask, vaddr_t start,
+                           size_t size, unsigned long vmid)
+{
+    ASSERT(sbi_rfence);
+
+    return sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
+                      cpu_mask, start, size, vmid, 0);
+}
+
 /* This function must always succeed. */
 #define sbi_get_spec_version()  \
     sbi_ext_base_func(SBI_EXT_BASE_GET_SPEC_VERSION)
-- 
2.49.0

Re: [PATCH v2 02/17] xen/riscv: introduce sbi_remote_hfence_gvma_vmid()

Posted by Jan Beulich 4 months, 2 weeks ago

On 10.06.2025 15:05, Oleksii Kurochko wrote:
> It instructs the remote harts to execute one or more HFENCE.GVMA instructions
> by making an SBI call, covering the range of guest physical addresses between
> start_addr and start_addr + size only for the given VMID.
> 
> This function call is only valid for harts implementing hypervisor extension.

We require H now, don't we? It's also odd to have this here, but not in patch 1.

> --- a/xen/arch/riscv/sbi.c
> +++ b/xen/arch/riscv/sbi.c
> @@ -267,6 +267,15 @@ int sbi_remote_hfence_gvma(const cpumask_t *cpu_mask, vaddr_t start,
>                        cpu_mask, start, size, 0, 0);
>  }
>  
> +int sbi_remote_hfence_gvma_vmid(const cpumask_t *cpu_mask, vaddr_t start,
> +                           size_t size, unsigned long vmid)
> +{
> +    ASSERT(sbi_rfence);
> +
> +    return sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
> +                      cpu_mask, start, size, vmid, 0);
> +}

sbi_remote_hfence_gvma() may want implementing in terms of this new function,
requiring the patches to be swapped. Provided (see comment there) that helper
is actually needed.

Jan

Re: [PATCH v2 02/17] xen/riscv: introduce sbi_remote_hfence_gvma_vmid()

Posted by Oleksii Kurochko 4 months, 1 week ago

On 6/18/25 5:20 PM, Jan Beulich wrote:
> On 10.06.2025 15:05, Oleksii Kurochko wrote:
>> It instructs the remote harts to execute one or more HFENCE.GVMA instructions
>> by making an SBI call, covering the range of guest physical addresses between
>> start_addr and start_addr + size only for the given VMID.
>>
>> This function call is only valid for harts implementing hypervisor extension.
> We require H now, don't we? It's also odd to have this here, but not in patch 1.

Yes, we required it. I will drop this part from the commit message and the comment
above declaration of sbi_remote_hfence_gvma_vmid().

>
>> --- a/xen/arch/riscv/sbi.c
>> +++ b/xen/arch/riscv/sbi.c
>> @@ -267,6 +267,15 @@ int sbi_remote_hfence_gvma(const cpumask_t *cpu_mask, vaddr_t start,
>>                         cpu_mask, start, size, 0, 0);
>>   }
>>   
>> +int sbi_remote_hfence_gvma_vmid(const cpumask_t *cpu_mask, vaddr_t start,
>> +                           size_t size, unsigned long vmid)
>> +{
>> +    ASSERT(sbi_rfence);
>> +
>> +    return sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
>> +                      cpu_mask, start, size, vmid, 0);
>> +}
> sbi_remote_hfence_gvma() may want implementing in terms of this new function,
> requiring the patches to be swapped. Provided (see comment there) that helper
> is actually needed.

It makes sense.
But it seems like there is no need for sbi_remote_hfence_gvma() as we have VMID introduced.

~ Oleksii