[xen staging] x86/idle: prevent entering C6 with in service interrupts on Intel

[patchbot@xxxxxxx]

commit fc44a7014cafe28b8c53eeaf6ac2a71f5bc8b815
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Fri May 22 16:07:38 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 22 16:07:38 2020 +0200

    x86/idle: prevent entering C6 with in service interrupts on Intel
    
    Apply a workaround for Intel errata BDX99, CLX30, SKX100, CFW125,
    BDF104, BDH85, BDM135, KWB131: "A Pending Fixed Interrupt May Be
    Dispatched Before an Interrupt of The Same Priority Completes".
    
    Apply the errata to all server and client models (big cores) from
    Broadwell to Cascade Lake. The workaround is grouped together with the
    existing fix for errata AAJ72, and the eoi from the function name is
    removed.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/acpi/cpu_idle.c  | 38 ++++++++++++++++++++++++++++++++++----
 xen/arch/x86/cpu/mwait-idle.c |  2 +-
 xen/include/asm-x86/cpuidle.h |  2 +-
 3 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index 82f108d301..178cb607c2 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -548,7 +548,7 @@ void trace_exit_reason(u32 *irq_traced)
     }
 }
 
-bool errata_c6_eoi_workaround(void)
+bool errata_c6_workaround(void)
 {
     static int8_t __read_mostly fix_needed = -1;
 
@@ -573,10 +573,40 @@ bool errata_c6_eoi_workaround(void)
             INTEL_FAM6_MODEL(0x2f),
             { }
         };
+        /*
+         * Errata BDX99, CLX30, SKX100, CFW125, BDF104, BDH85, BDM135, KWB131:
+         * A Pending Fixed Interrupt May Be Dispatched Before an Interrupt of
+         * The Same Priority Completes.
+         *
+         * Resuming from C6 Sleep-State, with Fixed Interrupts of the same
+         * priority queued (in the corresponding bits of the IRR and ISR APIC
+         * registers), the processor may dispatch the second interrupt (from
+         * the IRR bit) before the first interrupt has completed and written to
+         * the EOI register, causing the first interrupt to never complete.
+         */
+        static const struct x86_cpu_id isr_errata[] = {
+            /* Broadwell */
+            INTEL_FAM6_MODEL(0x47),
+            INTEL_FAM6_MODEL(0x3d),
+            INTEL_FAM6_MODEL(0x4f),
+            INTEL_FAM6_MODEL(0x56),
+            /* Skylake (client) */
+            INTEL_FAM6_MODEL(0x5e),
+            INTEL_FAM6_MODEL(0x4e),
+            /* {Sky/Cascade}lake (server) */
+            INTEL_FAM6_MODEL(0x55),
+            /* {Kaby/Coffee/Whiskey/Amber} Lake */
+            INTEL_FAM6_MODEL(0x9e),
+            INTEL_FAM6_MODEL(0x8e),
+            /* Cannon Lake */
+            INTEL_FAM6_MODEL(0x66),
+            { }
+        };
 #undef INTEL_FAM6_MODEL
 
-        fix_needed = cpu_has_apic && !directed_eoi_enabled &&
-                     x86_match_cpu(eoi_errata);
+        fix_needed = cpu_has_apic &&
+                     ((!directed_eoi_enabled && x86_match_cpu(eoi_errata)) ||
+                      x86_match_cpu(isr_errata));
     }
 
     return (fix_needed && cpu_has_pending_apic_eoi());
@@ -685,7 +715,7 @@ static void acpi_processor_idle(void)
         return;
     }
 
-    if ( (cx->type >= ACPI_STATE_C3) && errata_c6_eoi_workaround() )
+    if ( (cx->type >= ACPI_STATE_C3) && errata_c6_workaround() )
         cx = power->safe_state;
 
 
diff --git a/xen/arch/x86/cpu/mwait-idle.c b/xen/arch/x86/cpu/mwait-idle.c
index 88a3e160c5..52eab81bf8 100644
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -770,7 +770,7 @@ static void mwait_idle(void)
                return;
        }
 
-       if ((cx->type >= 3) && errata_c6_eoi_workaround())
+       if ((cx->type >= 3) && errata_c6_workaround())
                cx = power->safe_state;
 
        eax = cx->address;
diff --git a/xen/include/asm-x86/cpuidle.h b/xen/include/asm-x86/cpuidle.h
index 51368694dc..0981a8fd64 100644
--- a/xen/include/asm-x86/cpuidle.h
+++ b/xen/include/asm-x86/cpuidle.h
@@ -26,6 +26,6 @@ void update_idle_stats(struct acpi_processor_power *,
 void update_last_cx_stat(struct acpi_processor_power *,
                          struct acpi_processor_cx *, uint64_t);
 
-bool errata_c6_eoi_workaround(void);
+bool errata_c6_workaround(void);
 
 #endif /* __X86_ASM_CPUIDLE_H__ */
--
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