Merge tag 'x86_sev_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

- Convert the sev-guest plaform ->remove callback to return void

- Move the SEV C-bit verification to the BSP as it needs to happen only
once and not on every AP

* tag 'x86_sev_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
virt: sev-guest: Convert to platform remove callback returning void
x86/sev: Do the C-bit verification only on the BSP

arch/x86/kernel/head_64.S

···
 
 	/* Form the CR3 value being sure to include the CR3 modifier */
 	addq	$(early_top_pgt - __START_KERNEL_map), %rax
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	mov	%rax, %rdi
+	mov	%rax, %r14
+
+	addq	phys_base(%rip), %rdi
+
+	/*
+	 * For SEV guests: Verify that the C-bit is correct. A malicious
+	 * hypervisor could lie about the C-bit position to perform a ROP
+	 * attack on the guest by writing to the unencrypted stack and wait for
+	 * the next RET instruction.
+	 */
+	call	sev_verify_cbit
+
+	/*
+	 * Restore CR3 value without the phys_base which will be added
+	 * below, before writing %cr3.
+	 */
+	 mov	%r14, %rax
+#endif
+
 	jmp 1f
 SYM_CODE_END(startup_64)
 
···
 
 	/* Setup early boot stage 4-/5-level pagetables. */
 	addq	phys_base(%rip), %rax
-
-	/*
-	 * For SEV guests: Verify that the C-bit is correct. A malicious
-	 * hypervisor could lie about the C-bit position to perform a ROP
-	 * attack on the guest by writing to the unencrypted stack and wait for
-	 * the next RET instruction.
-	 */
-	movq	%rax, %rdi
-	call	sev_verify_cbit
 
 	/*
 	 * Switch to new page-table

drivers/virt/coco/sev-guest/sev-guest.c

···
 	return ret;
 }
 
-static int __exit sev_guest_remove(struct platform_device *pdev)
+static void __exit sev_guest_remove(struct platform_device *pdev)
 {
 	struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev);
 
···
 	free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg));
 	deinit_crypto(snp_dev->crypto);
 	misc_deregister(&snp_dev->misc);
-
-	return 0;
 }
 
 /*
···
  * with the SEV-SNP support, it is named "sev-guest".
  */
 static struct platform_driver sev_guest_driver = {
-	.remove		= __exit_p(sev_guest_remove),
+	.remove_new	= __exit_p(sev_guest_remove),
 	.driver		= {
 		.name = "sev-guest",
 	},