>>> Tim Deegan <Tim.Deegan@xxxxxxxxxx> 01.02.08 10:28 >>>
>At 08:45 +0000 on 01 Feb (1201855522), Jan Beulich wrote:
>> @@ -1034,8 +1047,10 @@ static int fixup_page_fault(unsigned lon
>> struct vcpu *v = current;
>> struct domain *d = v->domain;
>>
>> - /* No fixups in interrupt context or when interrupts are disabled. */
>> - if ( in_irq() || !(regs->eflags & X86_EFLAGS_IF) )
>> + /* No fixups in interrupt context, when interrupts are disabled, or
>> + * when a reserved bit was found to be set. */
>> + if ( in_irq() || !(regs->eflags & X86_EFLAGS_IF) ||
>> + (regs->error_code & PFEC_reserved_bit) )
>> return 0;
>>
>> if ( unlikely(IN_HYPERVISOR_RANGE(addr)) )
>
>The shadow pagetable code deliberately introduces invalid pagetable
>entries as part of its fast-path treatment of MMIO and not-present
>entries in the guest tables, so paging_fault needs to be called for
>PFEC_reserved_bit faults.
Here's a replacement patch then, it would still be questionable whether
reserved bit faults should ever be propagated to a guest...
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Index: 2008-01-28/xen/arch/x86/traps.c
===================================================================
--- 2008-01-28.orig/xen/arch/x86/traps.c 2008-01-28 11:31:44.000000000
+0100
+++ 2008-01-28/xen/arch/x86/traps.c 2008-02-01 11:25:49.000000000 +0100
@@ -823,6 +823,18 @@ asmlinkage void do_machine_check(struct
machine_check_vector(regs, regs->error_code);
}
+static inline void reserved_bit_page_fault(int guest, unsigned long addr,
+ struct cpu_user_regs *regs)
+{
+ if ( guest )
+ gdprintk(XENLOG_ERR, "");
+ else
+ dprintk(XENLOG_ERR, "");
+ printk("reserved bit in page table (ec=%04X): ", regs->error_code);
+ show_page_walk(addr);
+ show_execution_state(regs);
+}
+
void propagate_page_fault(unsigned long addr, u16 error_code)
{
struct trap_info *ti;
@@ -852,6 +864,8 @@ void propagate_page_fault(unsigned long
v->domain->domain_id, v->vcpu_id, error_code);
show_page_walk(addr);
}
+ else if ( unlikely(error_code & PFEC_reserved_bit) )
+ reserved_bit_page_fault(1, addr, guest_cpu_user_regs());
}
static int handle_gdt_ldt_mapping_fault(
@@ -1047,7 +1061,8 @@ static int fixup_page_fault(unsigned lon
trace_trap_two_addr(TRC_PV_PAGING_FIXUP, regs->eip, addr);
return ret;
}
- if ( (addr >= GDT_LDT_VIRT_START) && (addr < GDT_LDT_VIRT_END) )
+ if ( !(regs->error_code & PFEC_reserved_bit) &&
+ (addr >= GDT_LDT_VIRT_START) && (addr < GDT_LDT_VIRT_END) )
return handle_gdt_ldt_mapping_fault(
addr - GDT_LDT_VIRT_START, regs);
return 0;
@@ -1057,7 +1072,8 @@ static int fixup_page_fault(unsigned lon
guest_kernel_mode(v, regs) &&
/* Do not check if access-protection fault since the page may
legitimately be not present in shadow page tables */
- ((regs->error_code & PFEC_write_access) == PFEC_write_access) &&
+ ((regs->error_code & (PFEC_write_access|PFEC_reserved_bit)) ==
+ PFEC_write_access) &&
ptwr_do_page_fault(v, addr, regs) )
return EXCRET_fault_fixed;
@@ -1101,6 +1117,8 @@ asmlinkage void do_page_fault(struct cpu
if ( likely((fixup = search_exception_table(regs->eip)) != 0) )
{
perfc_incr(copy_user_faults);
+ if ( unlikely(regs->error_code & PFEC_reserved_bit) )
+ reserved_bit_page_fault(0, addr, regs);
regs->eip = fixup;
return;
}
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