PF2GUC_UPDATE_VGT_POLICY(9)

💅 PF2GUC_UPDATE_VGT_POLICY ✨

okay so bestie, welcome to the Kernel API Manual entry for PF2GUC_UPDATE_VGT_POLICY — this is the PF-side glow-up message, and it's literally the way the PF sets the GuC VGT Policy KLVs_ 🎀

no cap, the one thing you cannot forget: this message must be sent as a CTB HXG Message. that's not optional, that's the whole vibe check 🫶

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🌸 the request message (what you send)

here's the dword-0 layout, bestie — read those bit ranges carefully 👑

• Bits 31 — ORIGIN = GUC_HXG_ORIGIN_HOST_
• Bits 30:28 — TYPE = GUC_HXG_TYPE_REQUEST_
• Bits 27:16 — MBZ (must be zero, so like… don't touch it 🙈)
• Bits 15:0 — ACTION = GUC_ACTION_PF2GUC_UPDATE_VGT_POLICY = 0x5502

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🦋 the payload dwords (the main character energy)

1   31:0   **CFG_ADDR_LO** - dword aligned GGTT offset that
           represents the start of `GuC VGT Policy KLVs`_ list.
2   31:0   **CFG_ADDR_HI** - upper 32 bits of above offset.
3   31:0   **CFG_SIZE** - size (in dwords) of the config buffer

let me say it plainer for you 💖

• Dword 1, bits 31:0 — CFG_ADDR_LO: the dword aligned GGTT offset that represents the start of the GuC VGT Policy KLVs_ list
• Dword 2, bits 31:0 — CFG_ADDR_HI: the upper 32 bits of that same offset above ⭐
• Dword 3, bits 31:0 — CFG_SIZE: the size, in dwords, of the config buffer 🍓

it's giving "low dword, high dword, how big" and honestly? iconic. periodt.

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💜 the response message (what comes back at you)

• Bits 31 — ORIGIN = GUC_HXG_ORIGIN_GUC_
• Bits 30:28 — TYPE = GUC_HXG_TYPE_RESPONSE_SUCCESS_
• Bits 27:0 — COUNT — the number of KLVs successfully applied 🔥

so yeah, COUNT is your little receipt — that's how many KLVs actually made it through 💅

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✨ SEE ALSO ✨

the kernel file lives right here, bestie: ./drivers/gpu/drm/xe/abi/guc_actions_sriov_abi.h 📁

and the whole friend group, no one left out 👑:

• GUC2PF_RELAY_FROM_VF(9)
• PF2GUC_RELAY_TO_VF(9)
• GUC2VF_RELAY_FROM_PF(9)
• VF2GUC_RELAY_TO_PF(9)
• GUC2PF_ADVERSE_EVENT(9)
• GUC2PF_VF_STATE_NOTIFY(9)
• VF2GUC_MATCH_VERSION(9)
• PF2GUC_UPDATE_VF_CFG(9)
• PF2GUC_VF_CONTROL(9)
• VF2GUC_VF_RESET(9)
• VF2GUC_RESFIX_DONE(9)
• VF2GUC_QUERY_SINGLE_KLV(9)
• PF2GUC_SAVE_RESTORE_VF(9)
• VF2GUC_RESFIX_START(9)

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ngl bestie, MBZ means must be zero. it's not a suggestion, it's the law. set it and the firmware will be like "girl what" 💀

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🎀 that's the whole page! this one ships from ./drivers/gpu/drm/xe/abi, dated October 2026, and it's filed under PF2GUC_UPDATE_VGT_POLICY(9) — go forth and set those VGT policy KLVs, you absolute icon 🌈💖✨