| Message ID | 1488979950-10872-2-git-send-email-yu.c.zhang@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Xen-devel [mailto:xen-devel-bounces@lists.xen.org] On Behalf Of Yu > Zhang > Sent: 08 March 2017 13:32 > To: xen-devel@lists.xen.org > Cc: zhiyuan.lv@intel.com > Subject: [Xen-devel] [PATCH v7 1/5] x86/ioreq server: Release the p2m lock > after mmio is handled. > > Routine hvmemul_do_io() may need to peek the p2m type of a gfn to > select the ioreq server. For example, operations on gfns with > p2m_ioreq_server type will be delivered to a corresponding ioreq > server, and this requires that the p2m type not be switched back > to p2m_ram_rw during the emulation process. To avoid this race > condition, we delay the release of p2m lock in > hvm_hap_nested_page_fault() > until mmio is handled. > > Note: previously in hvm_hap_nested_page_fault(), put_gfn() was moved > before the handling of mmio, due to a deadlock risk between the p2m > lock and the event lock(in commit 77b8dfe). Later, a per-event channel > lock was introduced in commit de6acb7, to send events. So we do not > need to worry about the deadlock issue. > > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Reviewed-by: Jan Beulich <jbeulich@suse.com> > --- > Cc: Paul Durrant <paul.durrant@citrix.com> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> Your cc-s seem to have been dropped by your mailer (or at least I can't see them in the mail header). You may want to send these again so that relevant folks actually get cc-ed. Paul > --- > xen/arch/x86/hvm/hvm.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c > index ccfae4f..a9db7f7 100644 > --- a/xen/arch/x86/hvm/hvm.c > +++ b/xen/arch/x86/hvm/hvm.c > @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, > unsigned long gla, > (npfec.write_access && > (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) ) > { > - __put_gfn(p2m, gfn); > - if ( ap2m_active ) > - __put_gfn(hostp2m, gfn); > - > rc = 0; > if ( unlikely(is_pvh_domain(currd)) ) > - goto out; > + goto out_put_gfn; > > if ( !handle_mmio_with_translation(gla, gpa >> PAGE_SHIFT, npfec) ) > hvm_inject_hw_exception(TRAP_gp_fault, 0); > rc = 1; > - goto out; > + goto out_put_gfn; > } > > /* Check if the page has been paged out */ > -- > 1.9.1 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > https://lists.xen.org/xen-devel
On 3/8/2017 10:06 PM, Paul Durrant wrote: >> -----Original Message----- >> From: Xen-devel [mailto:xen-devel-bounces@lists.xen.org] On Behalf Of Yu >> Zhang >> Sent: 08 March 2017 13:32 >> To: xen-devel@lists.xen.org >> Cc: zhiyuan.lv@intel.com >> Subject: [Xen-devel] [PATCH v7 1/5] x86/ioreq server: Release the p2m lock >> after mmio is handled. >> >> Routine hvmemul_do_io() may need to peek the p2m type of a gfn to >> select the ioreq server. For example, operations on gfns with >> p2m_ioreq_server type will be delivered to a corresponding ioreq >> server, and this requires that the p2m type not be switched back >> to p2m_ram_rw during the emulation process. To avoid this race >> condition, we delay the release of p2m lock in >> hvm_hap_nested_page_fault() >> until mmio is handled. >> >> Note: previously in hvm_hap_nested_page_fault(), put_gfn() was moved >> before the handling of mmio, due to a deadlock risk between the p2m >> lock and the event lock(in commit 77b8dfe). Later, a per-event channel >> lock was introduced in commit de6acb7, to send events. So we do not >> need to worry about the deadlock issue. >> >> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> >> Reviewed-by: Jan Beulich <jbeulich@suse.com> >> --- >> Cc: Paul Durrant <paul.durrant@citrix.com> >> Cc: Jan Beulich <jbeulich@suse.com> >> Cc: Andrew Cooper <andrew.cooper3@citrix.com> > Your cc-s seem to have been dropped by your mailer (or at least I can't see them in the mail header). You may want to send these again so that relevant folks actually get cc-ed. Thanks for your remind. Let me try again. This is strange because I had commented out supress-cc in my git config. Please ignore this thread, and sorry for the inconvenience. :-) Yu > Paul > >> --- >> xen/arch/x86/hvm/hvm.c | 8 ++------ >> 1 file changed, 2 insertions(+), 6 deletions(-) >> >> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c >> index ccfae4f..a9db7f7 100644 >> --- a/xen/arch/x86/hvm/hvm.c >> +++ b/xen/arch/x86/hvm/hvm.c >> @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, >> unsigned long gla, >> (npfec.write_access && >> (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) ) >> { >> - __put_gfn(p2m, gfn); >> - if ( ap2m_active ) >> - __put_gfn(hostp2m, gfn); >> - >> rc = 0; >> if ( unlikely(is_pvh_domain(currd)) ) >> - goto out; >> + goto out_put_gfn; >> >> if ( !handle_mmio_with_translation(gla, gpa >> PAGE_SHIFT, npfec) ) >> hvm_inject_hw_exception(TRAP_gp_fault, 0); >> rc = 1; >> - goto out; >> + goto out_put_gfn; >> } >> >> /* Check if the page has been paged out */ >> -- >> 1.9.1 >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xen.org >> https://lists.xen.org/xen-devel
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index ccfae4f..a9db7f7 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla, (npfec.write_access && (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) ) { - __put_gfn(p2m, gfn); - if ( ap2m_active ) - __put_gfn(hostp2m, gfn); - rc = 0; if ( unlikely(is_pvh_domain(currd)) ) - goto out; + goto out_put_gfn; if ( !handle_mmio_with_translation(gla, gpa >> PAGE_SHIFT, npfec) ) hvm_inject_hw_exception(TRAP_gp_fault, 0); rc = 1; - goto out; + goto out_put_gfn; } /* Check if the page has been paged out */