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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 02/18] xen/arm: Implement PSCI system suspend call (virtual interface)
The implementation consists of:
-Adding PSCI system suspend call as new PSCI function
-Trapping PSCI system_suspend HVC
-Implementing PSCI system suspend call (virtual interface that allows
guests to suspend themselves)
The PSCI system suspend should be called by a guest from its boot
VCPU. Non-boot VCPUs of the guest should be hot-unplugged using PSCI
CPU_OFF call prior to issuing PSCI system suspend. Interrupts that
are left enabled by the guest are assumed to be its wake-up interrupts.
Therefore, a wake-up interrupt triggers the resume of the guest. Guest
should resume regardless of the state of Xen (suspended or not).
When a guest calls PSCI system suspend the respective domain will be
suspended if the following conditions are met:
1) Given resume entry point is not invalid
2) Other (if any) VCPUs of the calling guest are hot-unplugged
If the conditions above are met the calling domain is labeled as
suspended and the calling VCPU is blocked. If nothing else wouldn't
be done the suspended domain would resume from the place where it
called PSCI system suspend. This is expected if processing of the PSCI
system suspend call fails. However, in the case of success the calling
guest should resume (continue execution after the wake-up) from the entry
point which is given as the first argument of the PSCI system suspend
call. In addition to the entry point, the guest expects to start within
the environment whose state matches the state after reset. This means
that the guest should find reset register values, MMU disabled, etc.
Thereby, the context of VCPU should be 'reset' (as if the system is
comming out of reset), the program counter should contain entry point,
which is 1st argument, and r0/x0 should contain context ID which is 2nd
argument of PSCI system suspend call. The context of VCPU is set
accordingly when the PSCI system suspend is processed, so that nothing
needs to be done on resume/wake-up path. However, in order to ensure that
this context doesn't get overwritten by the scheduler when scheduling out
this VCPU (would normally happen after the calling CPU is blocked), we need
to check whether to return early from ctxt_switch_from().
There are variables in domain structure to keep track of domain shutdown.
One of existing shutdown reason is 'suspend' which this patch is using to
track the suspend state of a domain. Those variables are used to determine
whether to early return from ctxt_switch_from() or not.
A suspended domain will resume after the Xen receives an interrupt which is
targeted to the domain, unblocks the domain's VCPU, and schedules it in.
When the VCPU is scheduled in, the VCPU context is already reset, and
contains the right resume entry point in program counter that will be
restored in ctxt_switch_to(). The only thing that needs to be done at this
point is to clear the variables that marked the domain state as suspended.
Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xxxxxxxxxx>
---
Changes in v2:
-Fix print to compile for arm32 and to align with Xen coding style
---
xen/arch/arm/Makefile | 1 +
xen/arch/arm/domain.c | 13 +++
xen/arch/arm/suspend.c | 166 +++++++++++++++++++++++++++++++++++++++
xen/arch/arm/vpsci.c | 19 +++++
xen/include/asm-arm/perfc_defn.h | 1 +
xen/include/asm-arm/psci.h | 2 +
xen/include/asm-arm/suspend.h | 16 ++++
xen/include/xen/sched.h | 1 +
8 files changed, 219 insertions(+)
create mode 100644 xen/arch/arm/suspend.c
create mode 100644 xen/include/asm-arm/suspend.h
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 23c5d9adbc..744b1a4dc8 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -43,6 +43,7 @@ obj-y += setup.o
obj-y += shutdown.o
obj-y += smp.o
obj-y += smpboot.o
+obj-y += suspend.o
obj-y += sysctl.o
obj-y += time.o
obj-y += traps.o
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index e594b48d81..7f8105465c 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -97,6 +97,11 @@ static void ctxt_switch_from(struct vcpu *p)
if ( is_idle_vcpu(p) )
return;
+ /* VCPU's context should not be saved if its domain is suspended */
+ if ( p->domain->is_shut_down &&
+ (p->domain->shutdown_code == SHUTDOWN_suspend) )
+ return;
+
p2m_save_state(p);
/* CP 15 */
@@ -181,6 +186,14 @@ static void ctxt_switch_to(struct vcpu *n)
if ( is_idle_vcpu(n) )
return;
+ /* If the domain was suspended, it is resuming now */
+ if ( n->domain->is_shut_down &&
+ (n->domain->shutdown_code == SHUTDOWN_suspend) )
+ {
+ n->domain->is_shut_down = 0;
+ n->domain->shutdown_code = SHUTDOWN_CODE_INVALID;
+ }
+
p2m_restore_state(n);
vpidr = READ_SYSREG32(MIDR_EL1);
diff --git a/xen/arch/arm/suspend.c b/xen/arch/arm/suspend.c
new file mode 100644
index 0000000000..9eea9214e1
--- /dev/null
+++ b/xen/arch/arm/suspend.c
@@ -0,0 +1,166 @@
+#include <xen/sched.h>
+#include <asm/cpufeature.h>
+#include <asm/event.h>
+#include <asm/psci.h>
+
+/* Reset values of VCPU architecture specific registers */
+static void vcpu_arch_reset(struct vcpu *v)
+{
+ v->arch.ttbr0 = 0;
+ v->arch.ttbr1 = 0;
+ v->arch.ttbcr = 0;
+
+ v->arch.csselr = 0;
+ v->arch.cpacr = 0;
+ v->arch.contextidr = 0;
+ v->arch.tpidr_el0 = 0;
+ v->arch.tpidrro_el0 = 0;
+ v->arch.tpidr_el1 = 0;
+ v->arch.vbar = 0;
+ if ( is_32bit_domain(v->domain) )
+ v->arch.dacr = 0;
+ v->arch.par = 0;
+#if defined(CONFIG_ARM_32)
+ v->arch.mair0 = 0;
+ v->arch.mair1 = 0;
+ v->arch.amair0 = 0;
+ v->arch.amair1 = 0;
+#else
+ v->arch.mair = 0;
+ v->arch.amair = 0;
+#endif
+ /* Fault Status */
+#if defined(CONFIG_ARM_32)
+ v->arch.dfar = 0;
+ v->arch.ifar = 0;
+ v->arch.dfsr = 0;
+#elif defined(CONFIG_ARM_64)
+ v->arch.far = 0;
+ v->arch.esr = 0;
+#endif
+
+ if ( is_32bit_domain(v->domain) )
+ v->arch.ifsr = 0;
+ v->arch.afsr0 = 0;
+ v->arch.afsr1 = 0;
+
+#ifdef CONFIG_ARM_32
+ v->arch.joscr = 0;
+ v->arch.jmcr = 0;
+#endif
+
+ if ( is_32bit_domain(v->domain) && cpu_has_thumbee )
+ {
+ v->arch.teecr = 0;
+ v->arch.teehbr = 0;
+ }
+}
+
+/*
+ * This function sets the context of current VCPU to the state which is
expected
+ * by the guest on resume. The expected VCPU state is:
+ * 1) pc to contain resume entry point (1st argument of PSCI SYSTEM_SUSPEND)
+ * 2) r0/x0 to contain context ID (2nd argument of PSCI SYSTEM_SUSPEND)
+ * 3) All other general purpose and system registers should have reset values
+ *
+ * Note: this function has to return void because it has to always succeed. In
+ * other words, this function is called from virtual PSCI SYSTEM_SUSPEND
+ * implementation, which can return only a limited number of possible errors,
+ * none of which could represent the fact that an error occurred when preparing
+ * the domain for suspend.
+ * Consequently, dynamic memory allocation cannot be done within this function,
+ * because if malloc fails the error has nowhere to propagate.
+ */
+static void vcpu_suspend(register_t epoint, register_t cid)
+{
+ /* Static allocation because dynamic would need a non-void return */
+ static struct vcpu_guest_context ctxt;
+ struct vcpu *v = current;
+
+ /* Make sure that VCPU guest regs are zeroied */
+ memset(&ctxt, 0, sizeof(ctxt));
+
+ /* Set non-zero values to the registers prior to copying */
+ ctxt.user_regs.pc64 = (u64)epoint;
+
+ if ( is_32bit_domain(current->domain) )
+ {
+ ctxt.user_regs.r0_usr = cid;
+ ctxt.user_regs.cpsr = PSR_GUEST32_INIT;
+
+ /* Thumb set is allowed only for 32-bit domain */
+ if ( epoint & 1 )
+ {
+ ctxt.user_regs.cpsr |= PSR_THUMB;
+ ctxt.user_regs.pc64 &= ~(u64)1;
+ }
+ }
+#ifdef CONFIG_ARM_64
+ else
+ {
+ ctxt.user_regs.x0 = cid;
+ ctxt.user_regs.cpsr = PSR_GUEST64_INIT;
+ }
+#endif
+ ctxt.sctlr = SCTLR_GUEST_INIT;
+ ctxt.flags = VGCF_online;
+
+ /* Reset architecture specific registers */
+ vcpu_arch_reset(v);
+
+ /* Initialize VCPU registers */
+ _arch_set_info_guest(v, &ctxt);
+}
+
+int32_t domain_suspend(register_t epoint, register_t cid)
+{
+ struct vcpu *v;
+ struct domain *d = current->domain;
+ bool is_thumb = epoint & 1;
+
+ dprintk(XENLOG_DEBUG,
+ "Dom%d suspend: epoint=0x%"PRIregister", cid=0x%"PRIregister"\n",
+ d->domain_id, epoint, cid);
+
+ /* THUMB set is not allowed with 64-bit domain */
+ if ( is_64bit_domain(d) && is_thumb )
+ return PSCI_INVALID_ADDRESS;
+
+ /* Ensure that all CPUs other than the calling one are offline */
+ for_each_vcpu ( d, v )
+ {
+ if ( v != current && is_vcpu_online(v) )
+ return PSCI_DENIED;
+ }
+
+ /*
+ * Prepare the calling VCPU for suspend (reset its context, save entry
point
+ * into pc and context ID into r0/x0 as specified by PSCI SYSTEM_SUSPEND)
+ */
+ vcpu_suspend(epoint, cid);
+
+ /*
+ * Set the domain state to suspended (will be cleared when the domain
+ * resumes, i.e. VCPU of this domain gets scheduled in).
+ */
+ d->is_shut_down = 1;
+ d->shutdown_code = SHUTDOWN_suspend;
+
+ /*
+ * The calling domain is suspended by blocking its last running VCPU. If an
+ * event is pending the domain will resume right away (VCPU will not block,
+ * but when scheduled in it will resume from the given entry point).
+ */
+ vcpu_block_unless_event_pending(current);
+
+ return PSCI_SUCCESS;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/vpsci.c b/xen/arch/arm/vpsci.c
index 9f4e5b8844..f7922be0c5 100644
--- a/xen/arch/arm/vpsci.c
+++ b/xen/arch/arm/vpsci.c
@@ -18,6 +18,7 @@
#include <asm/vgic.h>
#include <asm/vpsci.h>
#include <asm/event.h>
+#include <asm/suspend.h>
#include <public/sched.h>
@@ -210,6 +211,11 @@ static void do_psci_0_2_system_reset(void)
domain_shutdown(d,SHUTDOWN_reboot);
}
+static int32_t do_psci_1_0_system_suspend(register_t epoint, register_t cid)
+{
+ return domain_suspend(epoint, cid);
+}
+
static int32_t do_psci_1_0_features(uint32_t psci_func_id)
{
/* /!\ Ordered by function ID and not name */
@@ -227,6 +233,8 @@ static int32_t do_psci_1_0_features(uint32_t psci_func_id)
case PSCI_0_2_FN32_SYSTEM_OFF:
case PSCI_0_2_FN32_SYSTEM_RESET:
case PSCI_1_0_FN32_PSCI_FEATURES:
+ case PSCI_1_0_FN32_SYSTEM_SUSPEND:
+ case PSCI_1_0_FN64_SYSTEM_SUSPEND:
case ARM_SMCCC_VERSION_FID:
return 0;
default:
@@ -357,6 +365,17 @@ bool do_vpsci_0_2_call(struct cpu_user_regs *regs,
uint32_t fid)
return true;
}
+ case PSCI_1_0_FN32_SYSTEM_SUSPEND:
+ case PSCI_1_0_FN64_SYSTEM_SUSPEND:
+ {
+ register_t epoint = PSCI_ARG(regs,1);
+ register_t cid = PSCI_ARG(regs,2);
+
+ perfc_incr(vpsci_system_suspend);
+ PSCI_SET_RESULT(regs, do_psci_1_0_system_suspend(epoint, cid));
+ return true;
+ }
+
default:
return false;
}
diff --git a/xen/include/asm-arm/perfc_defn.h b/xen/include/asm-arm/perfc_defn.h
index 8922e9525a..a02d0adea8 100644
--- a/xen/include/asm-arm/perfc_defn.h
+++ b/xen/include/asm-arm/perfc_defn.h
@@ -32,6 +32,7 @@ PERFCOUNTER(vpsci_system_reset, "vpsci: system_reset")
PERFCOUNTER(vpsci_cpu_suspend, "vpsci: cpu_suspend")
PERFCOUNTER(vpsci_cpu_affinity_info, "vpsci: cpu_affinity_info")
PERFCOUNTER(vpsci_features, "vpsci: features")
+PERFCOUNTER(vpsci_system_suspend, "vpsci: system_suspend")
PERFCOUNTER(vcpu_kick, "vcpu: notify other vcpu")
diff --git a/xen/include/asm-arm/psci.h b/xen/include/asm-arm/psci.h
index 832f77afff..26462d0c47 100644
--- a/xen/include/asm-arm/psci.h
+++ b/xen/include/asm-arm/psci.h
@@ -43,10 +43,12 @@ void call_psci_system_reset(void);
#define PSCI_0_2_FN32_SYSTEM_OFF PSCI_0_2_FN32(8)
#define PSCI_0_2_FN32_SYSTEM_RESET PSCI_0_2_FN32(9)
#define PSCI_1_0_FN32_PSCI_FEATURES PSCI_0_2_FN32(10)
+#define PSCI_1_0_FN32_SYSTEM_SUSPEND PSCI_0_2_FN32(14)
#define PSCI_0_2_FN64_CPU_SUSPEND PSCI_0_2_FN64(1)
#define PSCI_0_2_FN64_CPU_ON PSCI_0_2_FN64(3)
#define PSCI_0_2_FN64_AFFINITY_INFO PSCI_0_2_FN64(4)
+#define PSCI_1_0_FN64_SYSTEM_SUSPEND PSCI_0_2_FN64(14)
/* PSCI v0.2 affinity level state returned by AFFINITY_INFO */
#define PSCI_0_2_AFFINITY_LEVEL_ON 0
diff --git a/xen/include/asm-arm/suspend.h b/xen/include/asm-arm/suspend.h
new file mode 100644
index 0000000000..de787d296a
--- /dev/null
+++ b/xen/include/asm-arm/suspend.h
@@ -0,0 +1,16 @@
+#ifndef __ASM_ARM_SUSPEND_H__
+#define __ASM_ARM_SUSPEND_H__
+
+int32_t domain_suspend(register_t epoint, register_t cid);
+
+#endif
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 3171eabfd6..1f4e86524f 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -24,6 +24,7 @@
#include <xen/wait.h>
#include <public/xen.h>
#include <public/domctl.h>
+#include <public/sched.h>
#include <public/sysctl.h>
#include <public/vcpu.h>
#include <public/vm_event.h>
--
2.13.0
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