From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH] pvh: change epte_get_entry_emt() for pvh mem types Date: Fri, 22 Nov 2013 10:52:21 +0000 Message-ID: <528F3765.8080806@eu.citrix.com> References: <20131121170051.424971fd@mantra.us.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131121170051.424971fd@mantra.us.oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Mukesh Rathor , "Xen-devel@lists.xensource.com" Cc: Keir Fraser , eddie.dong@intel.com, "Nakajima, Jun" , Jan Beulich , Roger Pau Monne List-Id: xen-devel@lists.xenproject.org On 22/11/13 01:00, Mukesh Rathor wrote: > For pvh guests, epte_get_entry_emt() is incorrectly returning WB for > all mem types because of the following check: > if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_IDENT_PT] ) > Skip the check for pvh guests. > > Also note, MTRR ranges are not maintained for pvh, and a solution is > being contrived using PAT. > > Signed-off-by: Mukesh Rathor > --- > xen/arch/x86/hvm/mtrr.c | 7 ++++++- > 1 files changed, 6 insertions(+), 1 deletions(-) > > diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c > index 4ff1e55..5427e1c 100644 > --- a/xen/arch/x86/hvm/mtrr.c > +++ b/xen/arch/x86/hvm/mtrr.c > @@ -693,7 +693,8 @@ uint8_t epte_get_entry_emt(struct domain *d, unsigned long gfn, mfn_t mfn, > ((d->vcpu == NULL) || ((v = d->vcpu[0]) == NULL)) ) > return MTRR_TYPE_WRBACK; > > - if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_IDENT_PT] ) > + if ( !is_pvh_vcpu(v) && > + !v->domain->arch.hvm_domain.params[HVM_PARAM_IDENT_PT] ) > return MTRR_TYPE_WRBACK; > > if ( !mfn_valid(mfn_x(mfn)) ) > @@ -717,6 +718,10 @@ uint8_t epte_get_entry_emt(struct domain *d, unsigned long gfn, mfn_t mfn, > return MTRR_TYPE_WRBACK; > } > > + /* MTRR ranges are not maintained for pvh. */ > + if ( is_pvh_vcpu(v) ) > + return MTRR_TYPE_WRBACK; > + > gmtrr_mtype = get_mtrr_type(&v->arch.hvm_vcpu.mtrr, (gfn << PAGE_SHIFT)); > hmtrr_mtype = get_mtrr_type(&mtrr_state, (mfn_x(mfn) << PAGE_SHIFT)); > return ((gmtrr_mtype <= hmtrr_mtype) ? gmtrr_mtype : hmtrr_mtype); So this will bypass the host mtrr settings, and always return WRBACK, even if in mtrr_state it was set to something lower. Presumably that "min(host,guest)" was there for a reason. Are you sure it's safe to just ignore it? This is why I suggested the following instead: gmtrr_mtype = is_hvm_domain(v) ? get_mtrr_type(&v->arch.hvm_vcpu.mtrr, (gfn << PAGE_SHIFT)) : MTRR_TYPE_WRBACK; -George