[viogpu] Reject resolutions exceeding framebuffer segment capacity

[xz-dev]

Add resolution validation in IsSupportedVidPn to prevent switching to resolutions that exceed the framebuffer segment size. This fixes an issue where dynamically resizing to a large resolution (e.g., via virt-manager window resize) would fail in CreateFrameBufferObj, leaving the display in an unrecoverable state.

Previously, when the requested resolution required more memory than the pre-allocated framebuffer segment, the driver would:

1. Destroy the existing working framebuffer
2. Fail to create the new larger framebuffer
3. Leave the display inactive with no way to recover

Now the driver checks the required framebuffer size against the segment capacity in IsSupportedVidPn and rejects unsupported resolutions early, allowing Windows to gracefully handle the situation.

[gemini-code-assist]

Summary of Changes

Hello @xz-dev, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a critical validation step within the viogpu driver to prevent display instability. By checking if a desired resolution's framebuffer requirements exceed the pre-allocated segment size early in the IsSupportedVidPn function, the driver can now gracefully reject unsupported resolutions. This avoids scenarios where attempting to switch to an overly large resolution would previously lead to a destroyed display state and an unrecoverable system, significantly enhancing the robustness of dynamic display resizing.

Highlights

• Resolution Validation: Implemented a new check within the IsSupportedVidPn function to validate if a requested display resolution's framebuffer requirements exceed the pre-allocated framebuffer segment capacity.
• Enhanced Stability: Prevents the display from entering an unrecoverable state by rejecting resolutions that would otherwise lead to a failure in framebuffer creation after destroying the existing display configuration.
• Graceful Error Handling: Allows Windows to gracefully handle unsupported resolutions by rejecting them early in the driver's IsSupportedVidPn call, rather than failing catastrophically during the mode switch.

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[YanVugenfirer]

[Jenkins CI]: Can one of the admins verify this patch?

[gemini-code-assist]

Code Review

This pull request correctly addresses a potential crash by adding validation to reject resolutions that exceed the framebuffer's capacity. The logic to check the required size against the segment size in IsSupportedVidPn is sound and prevents the driver from entering an unrecoverable state. I've included one suggestion to refactor the new code block for improved readability and robustness by consolidating resource cleanup and removing a hardcoded value.

[YanVugenfirer]

@xz-dev Sorry, I missed that the "Signed-off-by: Name " line is missing. Please add in all commits. It can be automated by git when you do "git commit" add "-s" command line parameter.

Thanks,
Yan

[xz-dev]

Code formatted