[Xen-devel] [PATCH 2/2] Xen/vMCE: bugfix to remove problematic is_vmce_ready check

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

>From 9098666db640183f894b9aec09599dd32dddb7fa Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@xxxxxxxxx>
Date: Sat, 27 Apr 2013 22:37:35 +0800
Subject: [PATCH 2/2] Xen/vMCE: bugfix to remove problematic is_vmce_ready check

is_vmce_ready() is problematic:
* For dom0, it checks if virq bind to dom0 mcelog driver. If not, it
results dom0 crash. However, it's problematic and overkilled since
mcelog as a dom0 feature could be enabled/disabled per dom0 option:
(XEN) MCE: This error page is ownded by DOM 0
(XEN) DOM0 not ready for vMCE
(XEN) domain_crash called from mcaction.c:133
(XEN) Domain 0 reported crashed by domain 32767 on cpu#31:
(XEN) Domain 0 crashed: rebooting machine in 5 seconds.
(XEN) Resetting with ACPI MEMORY or I/O RESET_REG.

* For dom0, if really need check, it should check whether vMCE
injection for dom0 ready (say, exception trap bounce check, which
has been done at inject_vmce()), not check dom0 mcelog ready (which
has been done at mce_softirq() before send global virq to dom0).

* For hvm, it checks whether guest vcpu has different virtual
family/model with that of host pcpu --> that's deprecated, since
vMCE has changed a lot, not bound to host MCE any more.

Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
---
 xen/arch/x86/cpu/mcheck/mcaction.c |    6 ---
 xen/arch/x86/cpu/mcheck/vmce.c     |   68 ------------------------------------
 xen/arch/x86/cpu/mcheck/vmce.h     |    1 -
 3 files changed, 0 insertions(+), 75 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mcaction.c 
b/xen/arch/x86/cpu/mcheck/mcaction.c
index 0ac5b45..adf2ded 100644
--- a/xen/arch/x86/cpu/mcheck/mcaction.c
+++ b/xen/arch/x86/cpu/mcheck/mcaction.c
@@ -83,12 +83,6 @@ mc_memerr_dhandler(struct mca_binfo *binfo,
                 ASSERT(d);
                 gfn = get_gpfn_from_mfn((bank->mc_addr) >> PAGE_SHIFT);
 
-                if ( !is_vmce_ready(bank, d) )
-                {
-                    printk("DOM%d not ready for vMCE\n", d->domain_id);
-                    goto vmce_failed;
-                }
-
                 if ( unmmap_broken_page(d, _mfn(mfn), gfn) )
                 {
                     printk("Unmap broken memory %lx for DOM%d failed\n",
diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
index 7d3fac7..af3b491 100644
--- a/xen/arch/x86/cpu/mcheck/vmce.c
+++ b/xen/arch/x86/cpu/mcheck/vmce.c
@@ -413,74 +413,6 @@ int fill_vmsr_data(struct mcinfo_bank *mc_bank, struct 
domain *d,
     return 0;
 }
 
-static int is_hvm_vmce_ready(struct mcinfo_bank *bank, struct domain *d)
-{
-    struct vcpu *v;
-    int no_vmce = 0, i;
-
-    if (!is_hvm_domain(d))
-        return 0;
-
-    /* kill guest if not enabled vMCE */
-    for_each_vcpu(d, v)
-    {
-        if (!(v->arch.hvm_vcpu.guest_cr[4] & X86_CR4_MCE))
-        {
-            no_vmce = 1;
-            break;
-        }
-
-        if (!mce_broadcast)
-            break;
-    }
-
-    if (no_vmce)
-        return 0;
-
-    /* Guest has virtualized family/model information */
-    for ( i = 0; i < MAX_CPUID_INPUT; i++ )
-    {
-        if (d->arch.cpuids[i].input[0] == 0x1)
-        {
-            uint32_t veax = d->arch.cpuids[i].eax, vfam, vmod;
-
-                       vfam = (veax >> 8) & 15;
-                       vmod = (veax >> 4) & 15;
-
-            if (vfam == 0x6 || vfam == 0xf)
-                vmod += ((veax >> 16) & 0xF) << 4;
-                       if (vfam == 0xf)
-                               vfam += (veax >> 20) & 0xff;
-
-            if ( ( vfam != boot_cpu_data.x86 ) ||
-                 (vmod != boot_cpu_data.x86_model) )
-            {
-                dprintk(XENLOG_WARNING,
-                    "No vmce for different virtual family/model cpuid\n");
-                no_vmce = 1;
-            }
-            break;
-        }
-    }
-
-    if (no_vmce)
-        return 0;
-
-    return 1;
-}
-
-int is_vmce_ready(struct mcinfo_bank *bank, struct domain *d)
-{
-    if ( d == dom0)
-        return dom0_vmce_enabled();
-
-    /* No vMCE to HVM guest now */
-    if ( is_hvm_domain(d) )
-        return is_hvm_vmce_ready(bank, d);
-
-    return 0;
-}
-
 /* It's said some ram is setup as mmio_direct for UC cache attribute */
 #define P2M_UNMAP_TYPES (p2m_to_mask(p2m_ram_rw) \
                                 | p2m_to_mask(p2m_ram_logdirty) \
diff --git a/xen/arch/x86/cpu/mcheck/vmce.h b/xen/arch/x86/cpu/mcheck/vmce.h
index 7263deb..6b2c95a 100644
--- a/xen/arch/x86/cpu/mcheck/vmce.h
+++ b/xen/arch/x86/cpu/mcheck/vmce.h
@@ -8,7 +8,6 @@ int vmce_init(struct cpuinfo_x86 *c);
 #define dom0_vmce_enabled() (dom0 && dom0->max_vcpus && dom0->vcpu[0] \
         && guest_enabled_event(dom0->vcpu[0], VIRQ_MCA))
 
-int is_vmce_ready(struct mcinfo_bank *bank, struct domain *d);
 int unmmap_broken_page(struct domain *d, mfn_t mfn, unsigned long gfn);
 
 int vmce_intel_rdmsr(const struct vcpu *, uint32_t msr, uint64_t *val);
-- 
1.7.1

Attachment: 0002-Xen-vMCE-bugfix-to-remove-problematic-is_vmce_ready-.patch
Description: 0002-Xen-vMCE-bugfix-to-remove-problematic-is_vmce_ready-.patch

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