On 04/16/2018 11:21 PM, George Dunlap wrote:
> On Mon, Apr 16, 2018 at 7:46 PM, Razvan Cojocaru
> <[email protected]> wrote:
>> On 04/16/2018 08:47 PM, George Dunlap wrote:
>>> On 04/13/2018 03:44 PM, Razvan Cojocaru wrote:
>>>> On 04/11/2018 11:04 AM, Razvan Cojocaru wrote:
>>>>> Debugging continues.
>>>>
>>>> Finally, the attached patch seems to get the display unstuck in my
>>>> scenario, although for one guest I get:
>>>>
>>>> (XEN) d2v0 Unexpected vmexit: reason 49
>>>> (XEN) domain_crash called from vmx.c:4120
>>>> (XEN) Domain 2 (vcpu#0) crashed on cpu#1:
>>>> (XEN) ----[ Xen-4.11-unstable x86_64 debug=y Not tainted ]----
>>>> (XEN) CPU: 1
>>>> (XEN) RIP: 0010:[<fffff96000842354>]
>>>> (XEN) RFLAGS: 0000000000010246 CONTEXT: hvm guest (d2v0)
>>>> (XEN) rax: fffff88003000000 rbx: fffff900c0083db0 rcx: 00000000aa55aa55
>>>> (XEN) rdx: fffffa80041bdc41 rsi: fffff900c00c69a0 rdi: 0000000000000001
>>>> (XEN) rbp: 0000000000000000 rsp: fffff88002ee9ef0 r8: fffffa80041bdc40
>>>> (XEN) r9: fffff80001810e80 r10: fffffa800342aa70 r11: fffff88002ee9e80
>>>> (XEN) r12: 0000000000000005 r13: 0000000000000001 r14: fffff900c00c08b0
>>>> (XEN) r15: 0000000000000001 cr0: 0000000080050031 cr4: 00000000000406f8
>>>> (XEN) cr3: 00000000ef771000 cr2: fffff900c00c8000
>>>> (XEN) fsb: 00000000fffde000 gsb: fffff80001810d00 gss: 000007fffffdc000
>>>> (XEN) ds: 002b es: 002b fs: 0053 gs: 002b ss: 0018 cs: 0010
>>>>
>>>> i.e. EXIT_REASON_EPT_MISCONFIG - so not of the woods yet. I am hoping
>>>> somebody more familiar with the code can point to a more elegant
>>>> solution if one exists.
>>>
>>> I think I have an idea what's going on, but it's complicated. :-)
>>>
>>> Basically, the logdirty functionality isn't simple, and needs careful
>>> thought on how to integrate it. I'll write some more tomorrow, and see
>>> if I can come up with a solution.
>>
>> I think I know why this happens for the one guest - the other guests
>> start at a certain resolution display-wise and stay that way until shutdown.
>>
>> This particular guest starts with a larger screen, then goes to roughly
>> 2/3rds of it, then tries to go back to the initial larger one - at which
>> point the above happens. I assume this corresponds to some pages being
>> removed and/or added. I'll test this theory more tomorrow - if it's
>> correct I should be able to reproduce the crash (with the patch) by
>> simply resetting the screen resolution (increasing it).
>
> The trick is that p2m_change_type doesn't actually iterate over the
> entire p2m range, individually changing entries as it goes. Instead
> it misconfigures the entries at the top-level, which causes the kinds
> of faults shown above. As it gets faults for each entry, it checks
> the current type, the logdirty ranges, and the global logdirty bit to
> determine what the new types should be.
>
> Your patch makes it so that all the altp2ms now get the
> misconfiguration when the logdirty range is changed; but clearly
> handling the misconfiguration isn't integrated properly with the
> altp2m system yet. Doing it right may take some thought.
FWIW, the attached patch has solved the misconfig-related domain crash
for me (though I'm very likely missing some subtleties). It all seems to
work as expected when enabling altp2m and switching early to a new view.
However, now I have domUs with a frozen display when I disconnect the
introspection application (that is, after I switch back to the default
view and disable altp2m on the domain).
Thanks,
Razvan
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 14b5939..4530689 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -17,6 +17,7 @@
#include <xen/domain_page.h>
#include <xen/sched.h>
+#include <asm/altp2m.h>
#include <asm/current.h>
#include <asm/paging.h>
#include <asm/types.h>
@@ -652,17 +653,38 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
bool_t ept_handle_misconfig(uint64_t gpa)
{
struct vcpu *curr = current;
- struct p2m_domain *p2m = p2m_get_hostp2m(curr->domain);
+ struct domain *d = curr->domain;
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
bool_t spurious;
- int rc;
-
- p2m_lock(p2m);
+ int rc = 0;
+ unsigned int i;
spurious = curr->arch.hvm_vmx.ept_spurious_misconfig;
- rc = resolve_misconfig(p2m, PFN_DOWN(gpa));
- curr->arch.hvm_vmx.ept_spurious_misconfig = 0;
- p2m_unlock(p2m);
+ if ( altp2m_active(d) )
+ {
+ for ( i = 0; i < MAX_ALTP2M; i++ )
+ if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
+ {
+ p2m = d->arch.altp2m_p2m[i];
+
+ p2m_lock(p2m);
+
+ rc = resolve_misconfig(p2m, PFN_DOWN(gpa));
+ curr->arch.hvm_vmx.ept_spurious_misconfig = 0;
+
+ p2m_unlock(p2m);
+ }
+ }
+ else
+ {
+ p2m_lock(p2m);
+
+ rc = resolve_misconfig(p2m, PFN_DOWN(gpa));
+ curr->arch.hvm_vmx.ept_spurious_misconfig = 0;
+
+ p2m_unlock(p2m);
+ }
return spurious ? (rc >= 0) : (rc > 0);
}
@@ -1375,8 +1397,15 @@ void setup_ept_dump(void)
void p2m_init_altp2m_ept(struct domain *d, unsigned int i)
{
struct p2m_domain *p2m = d->arch.altp2m_p2m[i];
+ struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
struct ept_data *ept;
+ p2m->max_mapped_pfn = hostp2m->max_mapped_pfn;
+ p2m->default_access = hostp2m->default_access;
+ p2m->domain = hostp2m->domain;
+ p2m->logdirty_ranges = hostp2m->logdirty_ranges;
+ p2m->global_logdirty = hostp2m->global_logdirty;
+
p2m->min_remapped_gfn = gfn_x(INVALID_GFN);
p2m->max_remapped_gfn = 0;
ept = &p2m->ept;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index c53cab4..00f85e1 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -28,6 +28,7 @@
#include <xen/vm_event.h>
#include <xen/event.h>
#include <public/vm_event.h>
+#include <asm/altp2m.h>
#include <asm/domain.h>
#include <asm/page.h>
#include <asm/paging.h>
@@ -248,7 +249,6 @@ int p2m_init(struct domain *d)
int p2m_is_logdirty_range(struct p2m_domain *p2m, unsigned long start,
unsigned long end)
{
- ASSERT(p2m_is_hostp2m(p2m));
if ( p2m->global_logdirty ||
rangeset_contains_range(p2m->logdirty_ranges, start, end) )
return 1;
@@ -964,12 +964,12 @@ int p2m_change_type_one(struct domain *d, unsigned long gfn_l,
}
/* Modify the p2m type of a range of gfns from ot to nt. */
-void p2m_change_type_range(struct domain *d,
- unsigned long start, unsigned long end,
- p2m_type_t ot, p2m_type_t nt)
+static void _p2m_change_type_range(struct p2m_domain *p2m,
+ unsigned long start, unsigned long end,
+ p2m_type_t ot, p2m_type_t nt)
{
+ struct domain *d = p2m->domain;
unsigned long gfn = start;
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
int rc = 0;
ASSERT(ot != nt);
@@ -1022,6 +1022,23 @@ void p2m_change_type_range(struct domain *d,
p2m_unlock(p2m);
}
+void p2m_change_type_range(struct domain *d,
+ unsigned long start, unsigned long end,
+ p2m_type_t ot, p2m_type_t nt)
+{
+ unsigned int i;
+
+ if ( !altp2m_active(d) )
+ {
+ _p2m_change_type_range(p2m_get_hostp2m(d), start, end, ot, nt);
+ return;
+ }
+
+ for ( i = 0; i < MAX_ALTP2M; i++ )
+ if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
+ _p2m_change_type_range(d->arch.altp2m_p2m[i], start, end, ot, nt);
+}
+
/*
* Finish p2m type change for gfns which are marked as need_recalc in a range.
* Returns: 0/1 for success, negative for failure
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