[PATCH] x86/mce: handle DOMID_XEN properly in XEN_MC_msrinject

[PATCH] x86/mce: handle DOMID_XEN properly in XEN_MC_msrinject

[Haozhong Zhang]

Commit 26646f3 "x86/mce: translate passed-in GPA to host machine
address" forgot to consider dom_xen, which fails tools/xen-mceinj when
it's going to inject into domain DOMID_XEN (e.g. when -d option is not
used) via XEN_MC_msrinject. Use dom_xen when the domain id DOMID_XEN is
passed in.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
---
 xen/arch/x86/cpu/mcheck/mce.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index cc446eb..65de627 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -1427,17 +1427,18 @@ long do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) u_xen_mc)
 
         if ( mc_msrinject->mcinj_flags & MC_MSRINJ_F_GPADDR )
         {
-            struct domain *d;
+            domid_t domid = mc_msrinject->mcinj_domid;
+            struct domain *d = (domid == DOMID_XEN) ?
+                               dom_xen : get_domain_by_id(domid);
             struct mcinfo_msr *msr;
             unsigned int i;
             paddr_t gaddr;
             unsigned long gfn, mfn;
             p2m_type_t t;
 
-            d = get_domain_by_id(mc_msrinject->mcinj_domid);
             if ( d == NULL )
                 return x86_mcerr("do_mca inject: bad domain id %d",
-                                 -EINVAL, mc_msrinject->mcinj_domid);
+                                 -EINVAL, domid);
 
             for ( i = 0, msr = &mc_msrinject->mcinj_msr[0];
                   i < mc_msrinject->mcinj_count;
@@ -1452,7 +1453,7 @@ long do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) u_xen_mc)
                     put_gfn(d, gfn);
                     put_domain(d);
                     return x86_mcerr("do_mca inject: bad gfn %#lx of domain %d",
-                                     -EINVAL, gfn, mc_msrinject->mcinj_domid);
+                                     -EINVAL, gfn, domid);
                 }
 
                 msr->value = pfn_to_paddr(mfn) | (gaddr & (PAGE_SIZE - 1));
-- 
2.8.3


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Re: [PATCH] x86/mce: handle DOMID_XEN properly in XEN_MC_msrinject

[Egger, Christoph]

On 26/05/16 03:07, Haozhong Zhang wrote:
> Commit 26646f3 "x86/mce: translate passed-in GPA to host machine
> address" forgot to consider dom_xen, which fails tools/xen-mceinj when
> it's going to inject into domain DOMID_XEN (e.g. when -d option is not
> used) via XEN_MC_msrinject. Use dom_xen when the domain id DOMID_XEN is
> passed in.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>

Why not also consider DOMID_IO, DOMID_COW, DOMID_INVALID ?
In "nature" a memory error can happen everywhere anytime.

Christoph

> ---
>  xen/arch/x86/cpu/mcheck/mce.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
> index cc446eb..65de627 100644
> --- a/xen/arch/x86/cpu/mcheck/mce.c
> +++ b/xen/arch/x86/cpu/mcheck/mce.c
> @@ -1427,17 +1427,18 @@ long do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) u_xen_mc)
>  
>          if ( mc_msrinject->mcinj_flags & MC_MSRINJ_F_GPADDR )
>          {
> -            struct domain *d;
> +            domid_t domid = mc_msrinject->mcinj_domid;
> +            struct domain *d = (domid == DOMID_XEN) ?
> +                               dom_xen : get_domain_by_id(domid);
>              struct mcinfo_msr *msr;
>              unsigned int i;
>              paddr_t gaddr;
>              unsigned long gfn, mfn;
>              p2m_type_t t;
>  
> -            d = get_domain_by_id(mc_msrinject->mcinj_domid);
>              if ( d == NULL )
>                  return x86_mcerr("do_mca inject: bad domain id %d",
> -                                 -EINVAL, mc_msrinject->mcinj_domid);
> +                                 -EINVAL, domid);
>  
>              for ( i = 0, msr = &mc_msrinject->mcinj_msr[0];
>                    i < mc_msrinject->mcinj_count;
> @@ -1452,7 +1453,7 @@ long do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) u_xen_mc)
>                      put_gfn(d, gfn);
>                      put_domain(d);
>                      return x86_mcerr("do_mca inject: bad gfn %#lx of domain %d",
> -                                     -EINVAL, gfn, mc_msrinject->mcinj_domid);
> +                                     -EINVAL, gfn, domid);
>                  }
>  
>                  msr->value = pfn_to_paddr(mfn) | (gaddr & (PAGE_SIZE - 1));
> 

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Re: [PATCH] x86/mce: handle DOMID_XEN properly in XEN_MC_msrinject

[Haozhong Zhang]

On 05/26/16 09:15, Egger, Christoph wrote:
> On 26/05/16 03:07, Haozhong Zhang wrote:
> > Commit 26646f3 "x86/mce: translate passed-in GPA to host machine
> > address" forgot to consider dom_xen, which fails tools/xen-mceinj when
> > it's going to inject into domain DOMID_XEN (e.g. when -d option is not
> > used) via XEN_MC_msrinject. Use dom_xen when the domain id DOMID_XEN is
> > passed in.
> > 
> > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
> 
> Why not also consider DOMID_IO, DOMID_COW, DOMID_INVALID ?
> In "nature" a memory error can happen everywhere anytime.
>

This is to align to the original behavior before commit 26646f3 and a
later commit 4ddf474 "tools/xen-mceinj: Pass in GPA when injecting
through MSR_MCI_ADDR", which only supported injecting MCE of address
belonging to domains whose id is <= DOMID_FIRST_RESERVED (0x7FF0) or
DOMID_XEN (0x7FF2).

And I just found the fix in this patch is invalid. If a domain id >
DOMID_FIRST_RESERVED is passed, XEN_MC_msrinject should ensure that
MC_MSRINJ_F_GPADDR is not set in mc_msrinject->mcinj_flags and treat
the address passed-in as machine physical address (i.e. skip the
address translation in XEN_MCE_msrinject). In this way, DOMID_XEN,
DOMID_COW and DOMID_INVALID can be handled properly.

Thanks,
Haozhong

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