[XEN PATCH v2 1/2] x86/hvm: introduce config option for ACPI PM timer

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

Introduce config option X86_HVM_PMTIMER and make pmtimer emulation driver
configurable and possible to disable on systems that don't need it.
Option X86_X86_HVM_PMTIMER depends on HVM option, because this driver is part
of HVM support code.

Introduced additional check of domain's emulation flags, to cover the case
when user explicitly states the requirement of emulated devices that are
disabled in the build. HVM always require these devices to be present so domains
of this type can't be created when pmtimer or any other emulated device are
disabled.

Suggested-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
---
changes in v2:
 - updated description
 - renamed config option X86_PMTIMER -> X86_HVM_PMTIMER & moved related
   Kconfig changes to this patch
 - define X86_EMU_PM to 0 when !X86_HVM_PMTIMER
 - reverted changes to has_vpm() macro
 - moved emulation_flags_ok() checks to this patch
 - guard struct hvm_hw_acpi acpi attribute of struct domain
---
 xen/arch/x86/Kconfig                  | 13 +++++++++++++
 xen/arch/x86/domain.c                 |  7 ++++++-
 xen/arch/x86/hvm/Makefile             |  2 +-
 xen/arch/x86/include/asm/acpi.h       |  5 +++++
 xen/arch/x86/include/asm/domain.h     |  8 ++++++--
 xen/arch/x86/include/asm/hvm/domain.h |  2 ++
 xen/arch/x86/include/asm/hvm/vpt.h    | 10 ++++++++++
 7 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 9cdd04721a..ed0ece85c7 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -144,6 +144,19 @@ config INTEL_VMX
          If your system includes a processor with Intel VT-x support, say Y.
          If in doubt, say Y.
 
+menu "Emulated HVM devices support"
+       visible if EXPERT
+       depends on HVM
+
+config X86_HVM_PMTIMER
+       bool "ACPI PM timer emulation support"
+       default y
+       help
+         Build pmtimer driver that emulates ACPI PM timer for HVM/PVH guests.
+
+         If unsure, say Y.
+endmenu
+
 config XEN_SHSTK
        bool "Supervisor Shadow Stacks"
        depends on HAS_AS_CET_SS
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 78a13e6812..b340818ee2 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -742,11 +742,16 @@ int arch_sanitise_domain_config(struct 
xen_domctl_createdomain *config)
 
 static bool emulation_flags_ok(const struct domain *d, uint32_t emflags)
 {
-#ifdef CONFIG_HVM
+    const uint32_t disabled_emu_mask = X86_EMU_PM;
+
+#if defined(CONFIG_X86_HVM_PMTIMER)
     /* This doesn't catch !CONFIG_HVM case but it is better than nothing */
     BUILD_BUG_ON(X86_EMU_ALL != XEN_X86_EMU_ALL);
 #endif
 
+    if ( emflags & disabled_emu_mask )
+        return false;
+
     if ( is_hvm_domain(d) )
     {
         if ( is_hardware_domain(d) &&
diff --git a/xen/arch/x86/hvm/Makefile b/xen/arch/x86/hvm/Makefile
index 4c1fa5c6c2..3af8963218 100644
--- a/xen/arch/x86/hvm/Makefile
+++ b/xen/arch/x86/hvm/Makefile
@@ -18,7 +18,7 @@ obj-y += irq.o
 obj-y += monitor.o
 obj-y += mtrr.o
 obj-y += nestedhvm.o
-obj-y += pmtimer.o
+obj-$(CONFIG_X86_HVM_PMTIMER) += pmtimer.o
 obj-y += quirks.o
 obj-y += rtc.o
 obj-y += save.o
diff --git a/xen/arch/x86/include/asm/acpi.h b/xen/arch/x86/include/asm/acpi.h
index 217819dd61..eb2e4a1ede 100644
--- a/xen/arch/x86/include/asm/acpi.h
+++ b/xen/arch/x86/include/asm/acpi.h
@@ -150,8 +150,13 @@ void acpi_mmcfg_init(void);
 /* Incremented whenever we transition through S3. Value is 1 during boot. */
 extern uint32_t system_reset_counter;
 
+#ifdef CONFIG_X86_HVM_PMTIMER
 void hvm_acpi_power_button(struct domain *d);
 void hvm_acpi_sleep_button(struct domain *d);
+#else
+static inline void hvm_acpi_power_button(struct domain *d) {}
+static inline void hvm_acpi_sleep_button(struct domain *d) {}
+#endif
 
 /* suspend/resume */
 void save_rest_processor_state(void);
diff --git a/xen/arch/x86/include/asm/domain.h 
b/xen/arch/x86/include/asm/domain.h
index b79d6badd7..8550473997 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -463,7 +463,6 @@ struct arch_domain
 #ifdef CONFIG_HVM
 #define X86_EMU_LAPIC    XEN_X86_EMU_LAPIC
 #define X86_EMU_HPET     XEN_X86_EMU_HPET
-#define X86_EMU_PM       XEN_X86_EMU_PM
 #define X86_EMU_RTC      XEN_X86_EMU_RTC
 #define X86_EMU_IOAPIC   XEN_X86_EMU_IOAPIC
 #define X86_EMU_PIC      XEN_X86_EMU_PIC
@@ -474,7 +473,6 @@ struct arch_domain
 #else
 #define X86_EMU_LAPIC    0
 #define X86_EMU_HPET     0
-#define X86_EMU_PM       0
 #define X86_EMU_RTC      0
 #define X86_EMU_IOAPIC   0
 #define X86_EMU_PIC      0
@@ -484,6 +482,12 @@ struct arch_domain
 #define X86_EMU_VPCI     0
 #endif
 
+#ifdef CONFIG_X86_HVM_PMTIMER
+#define X86_EMU_PM       XEN_X86_EMU_PM
+#else
+#define X86_EMU_PM       0
+#endif
+
 #define X86_EMU_PIT     XEN_X86_EMU_PIT
 
 /* This must match XEN_X86_EMU_ALL in xen.h */
diff --git a/xen/arch/x86/include/asm/hvm/domain.h 
b/xen/arch/x86/include/asm/hvm/domain.h
index 333501d5f2..a4fddf7754 100644
--- a/xen/arch/x86/include/asm/hvm/domain.h
+++ b/xen/arch/x86/include/asm/hvm/domain.h
@@ -80,8 +80,10 @@ struct hvm_domain {
      * in public header files.
      * Internally, however, we will be using hvm_hw_acpi.
      */
+#ifdef CONFIG_X86_HVM_PMTIMER
 #define hvm_hw_acpi hvm_hw_pmtimer
     struct hvm_hw_acpi     acpi;
+#endif
 
     /* VCPU which is current target for 8259 interrupts. */
     struct vcpu           *i8259_target;
diff --git a/xen/arch/x86/include/asm/hvm/vpt.h 
b/xen/arch/x86/include/asm/hvm/vpt.h
index 0b92b28625..f24ef08925 100644
--- a/xen/arch/x86/include/asm/hvm/vpt.h
+++ b/xen/arch/x86/include/asm/hvm/vpt.h
@@ -187,10 +187,20 @@ void rtc_deinit(struct domain *d);
 void rtc_reset(struct domain *d);
 void rtc_update_clock(struct domain *d);
 
+#ifdef CONFIG_X86_HVM_PMTIMER
 void pmtimer_init(struct vcpu *v);
 void pmtimer_deinit(struct domain *d);
 void pmtimer_reset(struct domain *d);
 int pmtimer_change_ioport(struct domain *d, uint64_t version);
+#else
+static inline void pmtimer_init(struct vcpu *v) {}
+static inline void pmtimer_deinit(struct domain *d) {}
+static inline void pmtimer_reset(struct domain *d) {}
+static inline int pmtimer_change_ioport(struct domain *d, uint64_t version)
+{
+    return -ENODEV;
+}
+#endif
 
 void hpet_init(struct domain *d);
 void hpet_deinit(struct domain *d);
-- 
2.25.1