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From 5388ea3fc0737d1a659256ff3663057bef484c19 Mon Sep 17 00:00:00 2001
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From: Andrew Jones <drjones@redhat.com>
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Date: Fri, 31 Jan 2020 14:23:13 +0000
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Subject: [PATCH 11/15] target/arm/kvm: Implement virtual time adjustment
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Andrew Jones <drjones@redhat.com>
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Message-id: <20200131142314.13175-5-drjones@redhat.com>
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Patchwork-id: 93622
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O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH 4/5] target/arm/kvm: Implement virtual time adjustment
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Bugzilla: 1647366
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Auger Eric <eric.auger@redhat.com>
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RH-Acked-by: Gavin Shan <gshan@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1647366
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Author: Andrew Jones <drjones@redhat.com>
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Date:   Thu, 30 Jan 2020 16:02:06 +0000
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    target/arm/kvm: Implement virtual time adjustment
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    When a VM is stopped (such as when it's paused) guest virtual time
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    should stop counting. Otherwise, when the VM is resumed it will
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    experience time jumps and its kernel may report soft lockups. Not
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    counting virtual time while the VM is stopped has the side effect
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    of making the guest's time appear to lag when compared with real
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    time, and even with time derived from the physical counter. For
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    this reason, this change, which is enabled by default, comes with
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    a KVM CPU feature allowing it to be disabled, restoring legacy
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    behavior.
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    This patch only provides the implementation of the virtual time
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    adjustment. A subsequent patch will provide the CPU property
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    allowing the change to be enabled and disabled.
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    Reported-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
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    Signed-off-by: Andrew Jones <drjones@redhat.com>
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    Message-id: 20200120101023.16030-6-drjones@redhat.com
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    Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
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    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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(cherry picked from commit e5ac4200b4cddf44df9adbef677af0d1f1c579c6)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 target/arm/cpu.h     |  7 ++++
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 target/arm/kvm.c     | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
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 target/arm/kvm32.c   |  3 ++
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 target/arm/kvm64.c   |  3 ++
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 target/arm/kvm_arm.h | 38 ++++++++++++++++++++++
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 target/arm/machine.c |  7 ++++
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 6 files changed, 150 insertions(+)
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diff --git a/target/arm/cpu.h b/target/arm/cpu.h
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index 82dd3cc..fbd8ea0 100644
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--- a/target/arm/cpu.h
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+++ b/target/arm/cpu.h
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@@ -821,6 +821,13 @@ struct ARMCPU {
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     /* KVM init features for this CPU */
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     uint32_t kvm_init_features[7];
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+    /* KVM CPU state */
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+
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+    /* KVM virtual time adjustment */
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+    bool kvm_adjvtime;
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+    bool kvm_vtime_dirty;
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+    uint64_t kvm_vtime;
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+
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     /* Uniprocessor system with MP extensions */
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     bool mp_is_up;
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diff --git a/target/arm/kvm.c b/target/arm/kvm.c
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index 5b82cef..26d7f8b 100644
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--- a/target/arm/kvm.c
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+++ b/target/arm/kvm.c
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@@ -359,6 +359,22 @@ static int compare_u64(const void *a, const void *b)
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     return 0;
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 }
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+/*
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+ * cpreg_values are sorted in ascending order by KVM register ID
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+ * (see kvm_arm_init_cpreg_list). This allows us to cheaply find
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+ * the storage for a KVM register by ID with a binary search.
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+ */
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+static uint64_t *kvm_arm_get_cpreg_ptr(ARMCPU *cpu, uint64_t regidx)
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+{
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+    uint64_t *res;
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+
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+    res = bsearch(&regidx, cpu->cpreg_indexes, cpu->cpreg_array_len,
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+                  sizeof(uint64_t), compare_u64);
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+    assert(res);
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+
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+    return &cpu->cpreg_values[res - cpu->cpreg_indexes];
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+}
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+
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 /* Initialize the ARMCPU cpreg list according to the kernel's
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  * definition of what CPU registers it knows about (and throw away
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  * the previous TCG-created cpreg list).
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@@ -512,6 +528,23 @@ bool write_list_to_kvmstate(ARMCPU *cpu, int level)
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     return ok;
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 }
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+void kvm_arm_cpu_pre_save(ARMCPU *cpu)
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+{
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+    /* KVM virtual time adjustment */
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+    if (cpu->kvm_vtime_dirty) {
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+        *kvm_arm_get_cpreg_ptr(cpu, KVM_REG_ARM_TIMER_CNT) = cpu->kvm_vtime;
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+    }
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+}
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+
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+void kvm_arm_cpu_post_load(ARMCPU *cpu)
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+{
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+    /* KVM virtual time adjustment */
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+    if (cpu->kvm_adjvtime) {
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+        cpu->kvm_vtime = *kvm_arm_get_cpreg_ptr(cpu, KVM_REG_ARM_TIMER_CNT);
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+        cpu->kvm_vtime_dirty = true;
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+    }
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+}
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+
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 void kvm_arm_reset_vcpu(ARMCPU *cpu)
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 {
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     int ret;
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@@ -579,6 +612,50 @@ int kvm_arm_sync_mpstate_to_qemu(ARMCPU *cpu)
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     return 0;
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 }
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+void kvm_arm_get_virtual_time(CPUState *cs)
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+{
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+    ARMCPU *cpu = ARM_CPU(cs);
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+    struct kvm_one_reg reg = {
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+        .id = KVM_REG_ARM_TIMER_CNT,
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+        .addr = (uintptr_t)&cpu->kvm_vtime,
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+    };
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+    int ret;
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+
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+    if (cpu->kvm_vtime_dirty) {
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+        return;
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+    }
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+
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+    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, ®);
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+    if (ret) {
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+        error_report("Failed to get KVM_REG_ARM_TIMER_CNT");
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+        abort();
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+    }
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+
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+    cpu->kvm_vtime_dirty = true;
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+}
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+
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+void kvm_arm_put_virtual_time(CPUState *cs)
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+{
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+    ARMCPU *cpu = ARM_CPU(cs);
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+    struct kvm_one_reg reg = {
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+        .id = KVM_REG_ARM_TIMER_CNT,
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+        .addr = (uintptr_t)&cpu->kvm_vtime,
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+    };
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+    int ret;
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+
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+    if (!cpu->kvm_vtime_dirty) {
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+        return;
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+    }
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+
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+    ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
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+    if (ret) {
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+        error_report("Failed to set KVM_REG_ARM_TIMER_CNT");
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+        abort();
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+    }
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+
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+    cpu->kvm_vtime_dirty = false;
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+}
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+
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 int kvm_put_vcpu_events(ARMCPU *cpu)
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 {
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     CPUARMState *env = &cpu->env;
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@@ -690,6 +767,21 @@ MemTxAttrs kvm_arch_post_run(CPUState *cs, struct kvm_run *run)
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     return MEMTXATTRS_UNSPECIFIED;
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 }
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+void kvm_arm_vm_state_change(void *opaque, int running, RunState state)
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+{
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+    CPUState *cs = opaque;
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+    ARMCPU *cpu = ARM_CPU(cs);
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+
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+    if (running) {
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+        if (cpu->kvm_adjvtime) {
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+            kvm_arm_put_virtual_time(cs);
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+        }
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+    } else {
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+        if (cpu->kvm_adjvtime) {
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+            kvm_arm_get_virtual_time(cs);
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+        }
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+    }
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+}
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 int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
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 {
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diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
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index 32bf8d6..3a8b437 100644
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--- a/target/arm/kvm32.c
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+++ b/target/arm/kvm32.c
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@@ -16,6 +16,7 @@
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 #include "qemu-common.h"
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 #include "cpu.h"
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 #include "qemu/timer.h"
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+#include "sysemu/runstate.h"
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 #include "sysemu/kvm.h"
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 #include "kvm_arm.h"
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 #include "internals.h"
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@@ -198,6 +199,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
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         return -EINVAL;
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     }
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+    qemu_add_vm_change_state_handler(kvm_arm_vm_state_change, cs);
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+
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     /* Determine init features for this CPU */
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     memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
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     if (cpu->start_powered_off) {
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diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
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index 666a81a..d368189 100644
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--- a/target/arm/kvm64.c
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+++ b/target/arm/kvm64.c
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@@ -23,6 +23,7 @@
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 #include "qemu/host-utils.h"
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 #include "qemu/main-loop.h"
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 #include "exec/gdbstub.h"
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+#include "sysemu/runstate.h"
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 #include "sysemu/kvm.h"
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 #include "sysemu/kvm_int.h"
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 #include "kvm_arm.h"
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@@ -735,6 +736,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
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         return -EINVAL;
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     }
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+    qemu_add_vm_change_state_handler(kvm_arm_vm_state_change, cs);
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+
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     /* Determine init features for this CPU */
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     memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
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     if (cpu->start_powered_off) {
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diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
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index b48a9c9..01a9a18 100644
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--- a/target/arm/kvm_arm.h
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+++ b/target/arm/kvm_arm.h
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@@ -128,6 +128,23 @@ bool write_list_to_kvmstate(ARMCPU *cpu, int level);
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 bool write_kvmstate_to_list(ARMCPU *cpu);
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 /**
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+ * kvm_arm_cpu_pre_save:
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+ * @cpu: ARMCPU
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+ *
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+ * Called after write_kvmstate_to_list() from cpu_pre_save() to update
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+ * the cpreg list with KVM CPU state.
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+ */
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+void kvm_arm_cpu_pre_save(ARMCPU *cpu);
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+
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+/**
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+ * kvm_arm_cpu_post_load:
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+ * @cpu: ARMCPU
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+ *
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+ * Called from cpu_post_load() to update KVM CPU state from the cpreg list.
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+ */
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+void kvm_arm_cpu_post_load(ARMCPU *cpu);
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+
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+/**
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  * kvm_arm_reset_vcpu:
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  * @cpu: ARMCPU
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  *
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@@ -292,6 +309,24 @@ int kvm_arm_sync_mpstate_to_kvm(ARMCPU *cpu);
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  */
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 int kvm_arm_sync_mpstate_to_qemu(ARMCPU *cpu);
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+/**
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+ * kvm_arm_get_virtual_time:
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+ * @cs: CPUState
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+ *
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+ * Gets the VCPU's virtual counter and stores it in the KVM CPU state.
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+ */
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+void kvm_arm_get_virtual_time(CPUState *cs);
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+
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+/**
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+ * kvm_arm_put_virtual_time:
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+ * @cs: CPUState
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+ *
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+ * Sets the VCPU's virtual counter to the value stored in the KVM CPU state.
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+ */
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+void kvm_arm_put_virtual_time(CPUState *cs);
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+
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+void kvm_arm_vm_state_change(void *opaque, int running, RunState state);
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+
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 int kvm_arm_vgic_probe(void);
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 void kvm_arm_pmu_set_irq(CPUState *cs, int irq);
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@@ -339,6 +374,9 @@ static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq) {}
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 static inline void kvm_arm_pmu_init(CPUState *cs) {}
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 static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map) {}
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+
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+static inline void kvm_arm_get_virtual_time(CPUState *cs) {}
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+static inline void kvm_arm_put_virtual_time(CPUState *cs) {}
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 #endif
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 static inline const char *gic_class_name(void)
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diff --git a/target/arm/machine.c b/target/arm/machine.c
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index eb28b23..241890a 100644
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--- a/target/arm/machine.c
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+++ b/target/arm/machine.c
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@@ -642,6 +642,12 @@ static int cpu_pre_save(void *opaque)
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             /* This should never fail */
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             abort();
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         }
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+
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+        /*
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+         * kvm_arm_cpu_pre_save() must be called after
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+         * write_kvmstate_to_list()
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+         */
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+        kvm_arm_cpu_pre_save(cpu);
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     } else {
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         if (!write_cpustate_to_list(cpu, false)) {
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             /* This should never fail. */
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@@ -744,6 +750,7 @@ static int cpu_post_load(void *opaque, int version_id)
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          * we're using it.
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          */
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         write_list_to_cpustate(cpu);
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+        kvm_arm_cpu_post_load(cpu);
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     } else {
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         if (!write_list_to_cpustate(cpu)) {
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             return -1;
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-- 
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1.8.3.1
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