snp_svsm_vtpm_send_command(9)

💖 snp_svsm_vtpm_send_command(9) — the Kernel API Manual glow-up 🎀

okay so bestie, buckle up, because this is a kernel API function from the Kernel API Manual and it's lowkey iconic. It's called snp_svsm_vtpm_send_command and it does exactly what it says on the tin: executes a vTPM operation on SVSM. periodt.

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✨ NAME ✨

snp_svsm_vtpm_send_command — Execute a vTPM operation on SVSM 🦋

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🌸 SYNOPSIS 🌸

int snp_svsm_vtpm_send_command (u8 *buffer );

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💅 ARGUMENTS 💅

• buffer — a buffer that's doing double duty, no cap: you use it to both send the command and receive the response. one buffer, two jobs, main character energy fr fr. 🫶

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🌈 DESCRIPTION 🌈

So what it actually does: it executes an SVSM_VTPM_CMD call, as defined by "Secure VM Service Module for SEV-SNP Guests" Publication # 58019 Revision: 1.00. iykyk. 📚

Every single command request/response buffer shares a common structure, and the spec lays it out like this:

• Byte offset 0x000
• Size (Bytes) 4
• In/Out — In and Out (both, bestie, it swings both ways 💀)
• Description — In is the Platform command, Out is the Platform command response size

Each command can then build on top of that common request/response structure to make a structure that's specific to that command. it's giving customizable. 💖 For the deets, go peek at include/linux/tpm_svsm.h — more details live there.

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👑 RETURN 👑

• 0 on success 🎉
• -errno on failure 😭

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🦋 SEE ALSO 🦋

• Kernel file ./arch/x86/coco/sev/svsm.c
• snp_svsm_vtpm_probe(9)

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ngl, if you're poking at vTPM stuff on SEV-SNP guests, this is your girl. go off. 💜

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kisses and good vibes from ./arch/x86/coco/sev — this page was dated October 2026, mwah 💋✨