[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 8/9] xen/arm: Implement hypercall for dirty page tracing
>------- Original Message ------- >Sender : Julien Grall<julien.grall@xxxxxxxxxx> >Date : 2013-10-07 22:02 (GMT+09:00) >Title : Re: [Xen-devel] [PATCH v4 8/9] xen/arm: Implement hypercall for dirty >page tracing > >On 10/04/2013 05:44 AM, Jaeyong Yoo wrote: >> Add hypercall (shadow op: enable/disable and clean/peek dirted page bitmap). >> It consists of two parts: dirty page detecting and saving. >> For detecting, we setup the guest p2m's leaf PTE read-only and whenever >> the guest tries to write something, permission fault happens and traps into >> xen. >> The permission-faulted GPA should be saved for the toolstack (when it wants >> to see >> which pages are dirted). For this purpose, we temporarily save the GPAs into >> linked >> list by using 'add_mapped_vaddr' function and when toolstack wants >> (log_dirty_op function) the GPAs are copied into bitmap and the linnked list >> is flushed. >> >> Additionally, for supporting parallel migration of domUs, vlpt area should >> be context >> switched. >> >> Signed-off-by: Jaeyong Yoo >> --- > >[..] > >> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c >> index 4c0fc32..3b78ed2 100644 >> --- a/xen/arch/arm/traps.c >> +++ b/xen/arch/arm/traps.c >> @@ -1313,6 +1313,8 @@ static void do_trap_data_abort_guest(struct >> cpu_user_regs *regs, >> const char *msg; >> int rc, level = -1; >> mmio_info_t info; >> + int page_fault = ((dabt.dfsc & FSC_MASK) == >> + (FSC_FLT_PERM + FSC_3D_LEVEL) && dabt.write); >> >> if ( !check_conditional_instr(regs, hsr) ) >> { >> @@ -1327,22 +1329,23 @@ static void do_trap_data_abort_guest(struct >> cpu_user_regs *regs, >> info.gva = READ_SYSREG64(FAR_EL2); >> #endif >> >> - if (dabt.s1ptw) >> + if ( dabt.s1ptw && !page_fault ) > >I think checking !page_fault is nearly everywhere is error-prone when >this function will be modified. > >Can you do something like this? > >if ( page_fault ) > // Your code to handle page fault >else >{ > // handle_mmio >} > >It will avoid && !page_fault. That looks better. >> goto bad_data_abort; >> >> rc = gva_to_ipa(info.gva, &info.gpa); >> - if ( rc == -EFAULT ) >> + if ( rc == -EFAULT && !page_fault ) >> goto bad_data_abort; >> >> /* XXX: Decode the instruction if ISS is not valid */ >> - if ( !dabt.valid ) >> + if ( !dabt.valid && !page_fault ) >> goto bad_data_abort; >> >> /* >> * Erratum 766422: Thumb store translation fault to Hypervisor may >> * not have correct HSR Rt value. >> */ >> - if ( cpu_has_erratum_766422() && (regs->cpsr & PSR_THUMB) && dabt.write >> ) >> + if ( cpu_has_erratum_766422() && (regs->cpsr & PSR_THUMB) && dabt.write >> + && !page_fault) >> { >> rc = decode_instruction(regs, &info.dabt); >> if ( rc ) >> @@ -1358,6 +1361,16 @@ static void do_trap_data_abort_guest(struct >> cpu_user_regs *regs, >> return; >> } >> >> + /* handle permission fault on write */ >> + if ( page_fault ) >> + { >> + if ( current->domain->arch.dirty.mode == 0 ) >> + goto bad_data_abort; >> + >> + handle_page_fault(current->domain, info.gpa); > >You must call advance_pc(regs, hsr) here. I got it. > >> + return; >> + } >> + >> bad_data_abort: > >-- >Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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