[PATCH v2 05/32] gpu: nova-core: gsp: expose the VMMU segment size

[Zhi Wang <zhiw@nvidia.com>]

GSP_INIT reports the VMMU segment size needed to align vGPU guest memory
allocations.

Add a getter for the existing decoded value and propagate it into
GetGspStaticInfoReply. Keep zero when firmware omits the optional key.

Cc: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/gpu/nova-core/gsp/commands.rs    | 4 ++++
 drivers/gpu/nova-core/gsp/fw/commands.rs | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index 09223bc3b793..afc32c2a230e 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -53,6 +53,9 @@ pub(crate) struct GetGspStaticInfoReply {
     pub(crate) usable_fb_regions: KVec<Range<u64>>,
     /// Exclusive end of the FB physical address space.
     pub(crate) total_fb_end: u64,
+    /// VMMU segment size in bytes, or zero if GSP-RM omitted it.
+    #[expect(dead_code)]
+    pub(crate) vmmu_segment_size: u64,
 }
 
 /// Error type for [`GetGspStaticInfoReply::gpu_name`].
@@ -276,6 +279,7 @@ fn decode_gsp_info(words: &[u64]) -> Result<GetGspStaticInfoReply> {
         bar1_pde_base: decoded.bar1_pde_base(),
         usable_fb_regions,
         total_fb_end: decoded.total_fb_end().ok_or(EINVAL)?,
+        vmmu_segment_size: decoded.vmmu_segment_size(),
     })
 }
 
diff --git a/drivers/gpu/nova-core/gsp/fw/commands.rs b/drivers/gpu/nova-core/gsp/fw/commands.rs
index 2b9f8edb039d..c2e199688b79 100644
--- a/drivers/gpu/nova-core/gsp/fw/commands.rs
+++ b/drivers/gpu/nova-core/gsp/fw/commands.rs
@@ -367,6 +367,11 @@ pub(crate) fn total_fb_end(&self) -> Option<u64> {
             .max()?
             .checked_add(1)
     }
+
+    /// Returns the VMMU segment size in bytes, or zero if GSP-RM omitted it.
+    pub(in crate::gsp) const fn vmmu_segment_size(&self) -> u64 {
+        self.vmmu_segment_size
+    }
 }
 
 nvkv_decode! {