git: cc0080607d14 - stable/15 - x86: for wrmsr_early_safe(), catch all exceptions, not only #GP

The branch stable/15 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=cc0080607d14fe437ca0f0faa6999536df59acae

commit cc0080607d14fe437ca0f0faa6999536df59acae
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-05-27 08:21:10 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-06-04 00:34:43 +0000

    x86: for wrmsr_early_safe(), catch all exceptions, not only #GP
    
    (cherry picked from commit 0a02a47fd94a8326e84ac0a6cb857342b59671f8)
---
 sys/amd64/amd64/machdep.c | 24 +++++++++++++++---------
 sys/amd64/amd64/support.S |  7 +++----
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 2c69c1b3ace5..0d4ed59a98b1 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -1828,29 +1828,35 @@ wrmsr_early_safe_start(void)
 {
 	struct region_descriptor efi_idt;
 	struct gate_descriptor *gpf_descr;
+	int i;
 
 	sidt(&wrmsr_early_safe_orig_efi_idt);
 	efi_idt.rd_limit = 32 * sizeof(idt0[0]);
 	efi_idt.rd_base = (uintptr_t)idt0;
 	lidt(&efi_idt);
 
-	gpf_descr = &idt0[IDT_GP];
-	gpf_descr->gd_looffset = (uintptr_t)wrmsr_early_safe_gp_handler;
-	gpf_descr->gd_hioffset = (uintptr_t)wrmsr_early_safe_gp_handler >> 16;
-	gpf_descr->gd_selector = rcs();
-	gpf_descr->gd_type = SDT_SYSTGT;
-	gpf_descr->gd_p = 1;
+	/* Setup handler for all possible exceptions. */
+	for (i = 0; i < 32; i++) {
+		gpf_descr = &idt0[i];
+		gpf_descr->gd_looffset =
+		    (uintptr_t)wrmsr_early_safe_gp_handler;
+		gpf_descr->gd_hioffset =
+		    (uintptr_t)wrmsr_early_safe_gp_handler >> 16;
+		gpf_descr->gd_selector = rcs();
+		gpf_descr->gd_type = SDT_SYSTGT;
+		gpf_descr->gd_p = 1;
+	}
 }
 
 void
 wrmsr_early_safe_end(void)
 {
-	struct gate_descriptor *gpf_descr;
+	int i;
 
 	lidt(&wrmsr_early_safe_orig_efi_idt);
 
-	gpf_descr = &idt0[IDT_GP];
-	memset_early(gpf_descr, 0, sizeof(*gpf_descr));
+	for (i = 0; i < 32; i++)
+		memset_early(&idt0[i], 0, sizeof(idt0[0]));
 }
 
 #ifdef KDB
diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S
index 27694a95653c..547a37b37376 100644
--- a/sys/amd64/amd64/support.S
+++ b/sys/amd64/amd64/support.S
@@ -1566,20 +1566,19 @@ msr_onfault:
 	ret
 
 ENTRY(wrmsr_early_safe)
+	movq	%rsp,%r11
 	movl	%edi,%ecx
 	movl	%esi,%eax
 	sarq	$32,%rsi
 	movl	%esi,%edx
 	wrmsr
 	xorl	%eax,%eax
-wrmsr_early_faulted:
 	ret
 
 ENTRY(wrmsr_early_safe_gp_handler)
-	addq	$8,%rsp
+	movq	%r11,%rsp
 	movl	$EFAULT,%eax
-	movq	$wrmsr_early_faulted,(%rsp)
-	iretq
+	ret
 
 /*
  * void pmap_pti_pcid_invalidate(uint64_t ucr3, uint64_t kcr3);