From 943ac082804413a2f11d7330082095aa94def6c2 Mon Sep 17 00:00:00 2001
From: Gurchetan Singh <gurchetansingh@google.com>
Date: Wed, 17 Sep 2025 10:00:52 -0700
Subject: [PATCH] gfxstream: determine page size based on guest properties too

blobAlignment helps with running a 4KB guest on a 16KB host.
But for 16KB guest on 4KB host, we'll need to check guest
size too.  os_get_page_size(..) might not work on all target
guest OSes now, so default to 4KB.

TEST=CF 16KB works

Reviewed-by: David Gilhooley <djgilhooley.gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37460>
---
 .../GoldfishAddressSpace/VirtioGpuAddressSpaceStream.cpp    | 4 ++++
 src/gfxstream/guest/platform/drm/DrmVirtGpuDevice.cpp       | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/src/gfxstream/guest/GoldfishAddressSpace/VirtioGpuAddressSpaceStream.cpp b/src/gfxstream/guest/GoldfishAddressSpace/VirtioGpuAddressSpaceStream.cpp
index a1ac3edd3f5..62a860d197b 100644
--- a/src/gfxstream/guest/GoldfishAddressSpace/VirtioGpuAddressSpaceStream.cpp
+++ b/src/gfxstream/guest/GoldfishAddressSpace/VirtioGpuAddressSpaceStream.cpp
@@ -8,10 +8,13 @@
 #include <errno.h>
 
 #include "util/log.h"
+#include "util/os_misc.h"
 
 static bool GetRingParamsFromCapset(enum VirtGpuCapset capset, const VirtGpuCaps& caps,
                                     uint32_t& ringSize, uint32_t& bufferSize,
                                     uint32_t& blobAlignment) {
+    uint64_t guest_page_size = 4096;
+    os_get_page_size(&guest_page_size);
     switch (capset) {
         case kCapsetGfxStreamVulkan:
             ringSize = caps.vulkanCapset.ringSize;
@@ -37,6 +40,7 @@ static bool GetRingParamsFromCapset(enum VirtGpuCapset capset, const VirtGpuCaps
             return false;
     }
 
+    blobAlignment = std::max(blobAlignment, (uint32_t)guest_page_size);
     return true;
 }
 
diff --git a/src/gfxstream/guest/platform/drm/DrmVirtGpuDevice.cpp b/src/gfxstream/guest/platform/drm/DrmVirtGpuDevice.cpp
index 79a68d9331d..b22c336531f 100644
--- a/src/gfxstream/guest/platform/drm/DrmVirtGpuDevice.cpp
+++ b/src/gfxstream/guest/platform/drm/DrmVirtGpuDevice.cpp
@@ -20,6 +20,7 @@
 #include "drm-uapi/virtgpu_drm.h"
 #include "util/detect_os.h"
 #include "util/log.h"
+#include "util/os_misc.h"
 
 #ifdef MAJOR_IN_MKDEV
 #include <sys/mkdev.h>
@@ -243,6 +244,11 @@ int32_t DrmVirtGpuDevice::init(int32_t descriptor) {
         mCaps.vulkanCapset.blobAlignment = 4096;
     }
 
+    uint64_t guest_page_size = 4096;
+    os_get_page_size(&guest_page_size);
+    mCaps.vulkanCapset.blobAlignment =
+        std::max((uint32_t)guest_page_size, mCaps.vulkanCapset.blobAlignment);
+
     ctx_set_params[0].param = VIRTGPU_CONTEXT_PARAM_NUM_RINGS;
     ctx_set_params[0].value = 2;
     init.num_params = 1;