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Re: [Xen-devel] [PATCH 05/10] VMX: add help functions to support PML





On 03/28/2015 05:09 AM, Andrew Cooper wrote:
On 27/03/15 02:35, Kai Huang wrote:
This patch adds help functions to enable/disable PML, and flush PML buffer for
single vcpu and particular domain for further use.

Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
---
  xen/arch/x86/hvm/vmx/vmcs.c        | 190 +++++++++++++++++++++++++++++++++++++
  xen/include/asm-x86/hvm/vmx/vmcs.h |   9 ++
  2 files changed, 199 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 2798b0b..17cbef4 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1326,6 +1326,196 @@ void vmx_clear_eoi_exit_bitmap(struct vcpu *v, u8 
vector)
                  &v->arch.hvm_vmx.eoi_exitmap_changed);
  }
+int vmx_vcpu_pml_enabled(struct vcpu *v)
bool_t vmx_vcpu_pml_enabled(const struct vcpu *v)
Will do.


+{
+    return (v->arch.hvm_vmx.secondary_exec_control &
+            SECONDARY_EXEC_ENABLE_PML) ? 1 : 0;
This would be slightly shorter as
!!(v->arch.hvm_vmx.secondary_exec_control & SECONDARY_EXEC_ENABLE_PML)
Will do.


+}
+
+int vmx_vcpu_enable_pml(struct vcpu *v)
+{
+    struct domain *d = v->domain;
+
+    ASSERT(!vmx_vcpu_pml_enabled(v));
+
+    v->arch.hvm_vmx.pml_pg = d->arch.paging.alloc_page(d);
+    if ( !v->arch.hvm_vmx.pml_pg )
+        return -ENOMEM;
+
+    vmx_vmcs_enter(v);
+
+    __vmwrite(PML_ADDRESS, page_to_mfn(v->arch.hvm_vmx.pml_pg) << PAGE_SHIFT);
+    __vmwrite(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
+
+    v->arch.hvm_vmx.secondary_exec_control |= SECONDARY_EXEC_ENABLE_PML;
+
+    __vmwrite(SECONDARY_VM_EXEC_CONTROL,
+            v->arch.hvm_vmx.secondary_exec_control);
Alignment.
Do you mean to put 'v->arch.hvm_vmx.secondary_exec_control' to the same line with '__vmwrite(SECONDARY_VM_EXEC_CONTROL,'? In this case the number of characters will be 81.


+
+    vmx_vmcs_exit(v);
+
+    return 0;
+}
+
+void vmx_vcpu_disable_pml(struct vcpu *v)
+{
+    ASSERT(vmx_vcpu_pml_enabled(v));
+
+    vmx_vmcs_enter(v);
+
+    v->arch.hvm_vmx.secondary_exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
+    __vmwrite(SECONDARY_VM_EXEC_CONTROL,
+            v->arch.hvm_vmx.secondary_exec_control);
+
+    vmx_vmcs_exit(v);
+
+    v->domain->arch.paging.free_page(v->domain, v->arch.hvm_vmx.pml_pg);
+    v->arch.hvm_vmx.pml_pg = NULL;
+}
+
+void vmx_vcpu_flush_pml_buffer(struct vcpu *v)
+{
+    uint64_t *pml_buf;
+    unsigned long pml_idx;
+
+    ASSERT(vmx_vcpu_pml_enabled(v));
+
+    vmx_vmcs_enter(v);
+
+    __vmread(GUEST_PML_INDEX, &pml_idx);
+
+    /* Do nothing if PML buffer is empty */
+    if ( pml_idx == (PML_ENTITY_NUM - 1) )
+        goto out;
+
+    pml_buf = map_domain_page(page_to_mfn(v->arch.hvm_vmx.pml_pg));
__map_domain_page() is a wrapper which takes a struct page_info
Will do.


+
+    /*
+     * PML index can be either 2^16-1 (buffer is full), or 0~511 (buffer is not
+     * full), and in latter case PML index always points to next available
+     * entity.
+     */
+    if (pml_idx >= PML_ENTITY_NUM)
+        pml_idx = 0;
+    else
+        pml_idx++;
+
+    for ( ; pml_idx < PML_ENTITY_NUM; pml_idx++ )
+    {
+        struct p2m_domain *p2m = p2m_get_hostp2m(v->domain);
This p2m_get_host_p2m() call should be hoisted out of the loop.
Will do.


+        unsigned long gfn;
+        mfn_t mfn;
+        p2m_type_t t;
+        p2m_access_t a;
+
+        gfn = pml_buf[pml_idx] >> PAGE_SHIFT;
+        mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL);
+        if ( mfn_x(mfn) == INVALID_MFN )
+        {
+            /*
+             * Either EPT table entry for mapping the GFN has been destroyed, 
or
+             * there's something wrong with hardware behavior, in both cases we
+             * should report a warning.
+             */
+            dprintk(XENLOG_WARNING, "PML: vcpu %d: invalid GPA 0x%lx logged\n",
+                    v->vcpu_id, pml_buf[pml_idx]);
It would be shorter to log gfn rather than gpa.
Will do. And I'd also like to add the domain ID in the warning info.


+            continue;
+        }
+
+        /*
+         * Need to change type from log-dirty to normal memory for logged GFN.
+         * hap_track_dirty_vram depends on it to work. And we really only need
+         * to mark GFNs which hve been successfully changed from log-dirty to
+         * normal memory to be dirty.
+         */
+        if ( !p2m_change_type_one(v->domain, gfn, p2m_ram_logdirty,
+                    p2m_ram_rw) )
+            paging_mark_dirty(v->domain, mfn_x(mfn));
+    }
+
+    unmap_domain_page(pml_buf);
+
+    /* Reset PML index */
+    __vmwrite(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
+
+out:
+    vmx_vmcs_exit(v);
+}
+
+int vmx_domain_pml_enabled(struct domain *d)
bool_t and const as per vcpu variant.
Will do.


+{
+    return (d->arch.hvm_domain.vmx.status & VMX_DOMAIN_PML_ENABLED) ? 1 : 0;
+}
+
+/*
+ * This function enables PML for particular domain. It should be called when
+ * domain is paused.
In which case assert that the domain is paused, or call domain_pause()
yourself to take an extra pause refcount.
Which function should I use to assert domain is paused? I didn't find a function like "domain_paused". Is below good enough?

ASSERT(atomic_read(&d->pause_count));


+ *
+ * PML needs to be enabled globally for all vcpus of the domain, as PML buffer
+ * and PML index are pre-vcpu, but EPT table is shared by vcpus, therefore
+ * enabling PML on partial vcpus won't work.
+ */
+int vmx_domain_enable_pml(struct domain *d)
+{
+    struct vcpu *v;
+
+    ASSERT(!vmx_domain_pml_enabled(d));
+
+    for_each_vcpu( d, v )
+    {
+        if ( vmx_vcpu_enable_pml(v) )
+            goto error;
Please catch the actual rc from vmx_vcpu_enable_pml() and propagate out
of this function, rather than clobbering -ENOMEM with -EINVAL.

Also, per Xen style, you can drop the braces.
Will do. And I'll drop the braces in other functions I added in this patch as well.


~Andrew

+    }
+
+    d->arch.hvm_domain.vmx.status |= VMX_DOMAIN_PML_ENABLED;
+
+    return 0;
+
+error:
+    for_each_vcpu( d, v )
+    {
+        if ( vmx_vcpu_pml_enabled(v) )
+            vmx_vcpu_disable_pml(v);
+    }
+    return -EINVAL;
+}
+
+/*
+ * Disable PML for particular domain. Called when domain is paused.
+ *
+ * The same as enabling PML for domain, disabling PML should be done for all
+ * vcpus at once.
+ */
+void vmx_domain_disable_pml(struct domain *d)
+{
+    struct vcpu *v;
+
+    ASSERT(vmx_domain_pml_enabled(d));
+
+    for_each_vcpu( d, v )
+    {
+        vmx_vcpu_disable_pml(v);
+    }
+
+    d->arch.hvm_domain.vmx.status &= ~VMX_DOMAIN_PML_ENABLED;
+}
+
+/*
+ * Flush PML buffer of all vcpus, and update the logged dirty pages to 
log-dirty
+ * radix tree. Called when domain is paused.
+ */
+void vmx_domain_flush_pml_buffers(struct domain *d)
+{
+    struct vcpu *v;
+
+    ASSERT(vmx_domain_pml_enabled(d));
+
+    for_each_vcpu( d, v )
+    {
+        vmx_vcpu_flush_pml_buffer(v);
+    }
+}
+
  int vmx_create_vmcs(struct vcpu *v)
  {
      struct arch_vmx_struct *arch_vmx = &v->arch.hvm_vmx;
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 8cc1122..939d097 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -499,6 +499,15 @@ static inline int vmx_add_host_load_msr(u32 msr)
DECLARE_PER_CPU(bool_t, vmxon); +int vmx_vcpu_pml_enabled(struct vcpu *v);
+int vmx_vcpu_enable_pml(struct vcpu *v);
+void vmx_vcpu_disable_pml(struct vcpu *v);
+void vmx_vcpu_flush_pml_buffer(struct vcpu *v);
+int vmx_domain_pml_enabled(struct domain *d);
+int vmx_domain_enable_pml(struct domain *d);
+void vmx_domain_disable_pml(struct domain *d);
+void vmx_domain_flush_pml_buffers(struct domain *d);
+
  #endif /* ASM_X86_HVM_VMX_VMCS_H__ */
/*

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