[xen staging] x86/shutdown: change default reboot method preference

[patchbot@xxxxxxx]

commit d81dd31303513a1626973778d557a6493d86511a
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Aug 5 10:16:54 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Aug 5 10:16:54 2024 +0200

    x86/shutdown: change default reboot method preference
    
    The current logic to chose the preferred reboot method is based on the mode 
Xen
    has been booted into, so if the box is booted from UEFI, the preferred 
reboot
    method will be to use the ResetSystem() run time service call.
    
    However, that method seems to be widely untested, and quite often leads to a
    result similar to:
    
    Hardware Dom0 shutdown: rebooting machine
    ----[ Xen-4.18-unstable  x86_64  debug=y  Tainted:   C    ]----
    CPU:    0
    RIP:    e008:[<0000000000000017>] 0000000000000017
    RFLAGS: 0000000000010202   CONTEXT: hypervisor
    [...]
    Xen call trace:
       [<0000000000000017>] R 0000000000000017
       [<ffff83207eff7b50>] S ffff83207eff7b50
       [<ffff82d0403525aa>] F machine_restart+0x1da/0x261
       [<ffff82d04035263c>] F apic_wait_icr_idle+0/0x37
       [<ffff82d040233689>] F smp_call_function_interrupt+0xc7/0xcb
       [<ffff82d040352f05>] F call_function_interrupt+0x20/0x34
       [<ffff82d04033b0d5>] F do_IRQ+0x150/0x6f3
       [<ffff82d0402018c2>] F common_interrupt+0x132/0x140
       [<ffff82d040283d33>] F 
arch/x86/acpi/cpu_idle.c#acpi_idle_do_entry+0x113/0x129
       [<ffff82d04028436c>] F 
arch/x86/acpi/cpu_idle.c#acpi_processor_idle+0x3eb/0x5f7
       [<ffff82d04032a549>] F arch/x86/domain.c#idle_loop+0xec/0xee
    
    ****************************************
    Panic on CPU 0:
    FATAL TRAP: vector = 6 (invalid opcode)
    ****************************************
    
    Which in most cases does lead to a reboot, however that's unreliable.
    
    Change the default reboot preference to prefer ACPI over UEFI if available 
and
    not in reduced hardware mode.
    
    This is in line to what Linux does, so it's unlikely to cause issues on 
current
    and future hardware, since there's a much higher chance of vendors testing
    hardware with Linux rather than Xen.
    
    Add a special case for one Acer model that does require being rebooted using
    ResetSystem().  See Linux commit 0082517fa4bce for rationale.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Acked-By: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 CHANGELOG.md            |  2 ++
 xen/arch/x86/shutdown.c | 19 +++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index eeaaa8b274..5521ae5bb3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ The format is based on [Keep a 
Changelog](https://keepachangelog.com/en/1.0.0/)
 ## [4.20.0 
UNRELEASED](https://xenbits.xenproject.org/gitweb/?p=xen.git;a=shortlog;h=staging)
 - TBD
 
 ### Changed
+ - On x86:
+   - Prefer ACPI reboot over UEFI ResetSystem() run time service call.
 
 ### Added
 
diff --git a/xen/arch/x86/shutdown.c b/xen/arch/x86/shutdown.c
index acceec2a38..fa60d1638d 100644
--- a/xen/arch/x86/shutdown.c
+++ b/xen/arch/x86/shutdown.c
@@ -150,19 +150,20 @@ static void default_reboot_type(void)
 
     if ( xen_guest )
         reboot_type = BOOT_XEN;
+    else if ( !acpi_disabled && !acpi_gbl_reduced_hardware )
+        reboot_type = BOOT_ACPI;
     else if ( efi_enabled(EFI_RS) )
         reboot_type = BOOT_EFI;
-    else if ( acpi_disabled )
-        reboot_type = BOOT_KBD;
     else
-        reboot_type = BOOT_ACPI;
+        reboot_type = BOOT_KBD;
 }
 
 static int __init cf_check override_reboot(const struct dmi_system_id *d)
 {
     enum reboot_type type = (long)d->driver_data;
 
-    if ( type == BOOT_ACPI && acpi_disabled )
+    if ( (type == BOOT_ACPI && acpi_disabled) ||
+         (type == BOOT_EFI && !efi_enabled(EFI_RS)) )
         type = BOOT_KBD;
 
     if ( reboot_type != type )
@@ -172,6 +173,7 @@ static int __init cf_check override_reboot(const struct 
dmi_system_id *d)
             [BOOT_KBD]  = "keyboard controller",
             [BOOT_ACPI] = "ACPI",
             [BOOT_CF9]  = "PCI",
+            [BOOT_EFI]  = "UEFI",
         };
 
         reboot_type = type;
@@ -492,6 +494,15 @@ static const struct dmi_system_id __initconstrel 
reboot_dmi_table[] = {
             DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
             DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge R740")),
     },
+    {    /* Handle problems with rebooting on Acer TravelMate X514-51T. */
+        .callback = override_reboot,
+        .driver_data = (void *)(long)BOOT_EFI,
+        .ident = "Acer TravelMate X514-51T",
+        .matches = {
+            DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+            DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"),
+        },
+    },
     { }
 };
 
--
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