[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2 of 2] x86/mm: New mem access type to log access
xen/arch/x86/hvm/hvm.c | 1 + xen/arch/x86/mm/p2m-ept.c | 1 + xen/arch/x86/mm/p2m.c | 30 +++++++++++++++++++++--------- xen/include/asm-x86/p2m.h | 3 +++ xen/include/public/hvm/hvm_op.h | 3 +++ 5 files changed, 29 insertions(+), 9 deletions(-) This patch adds a new p2m access type, n2rwx. It allows for implement a "log access" mode in the hypervisor, aking to log dirty but for all types of accesses. Faults caused by this access mode automatically promote the access rights of the ofending p2m entry, place the event in the ring, and let the vcpu keep on executing. Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx> Signed-off-by: Adin Scannell <adin@xxxxxxxxxxx> diff -r e315ce73f082 -r 66ca1a02082f xen/arch/x86/hvm/hvm.c --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1250,6 +1250,7 @@ int hvm_hap_nested_page_fault(unsigned l switch (p2ma) { case p2m_access_n: + case p2m_access_n2rwx: default: violation = access_r || access_w || access_x; break; diff -r e315ce73f082 -r 66ca1a02082f xen/arch/x86/mm/p2m-ept.c --- a/xen/arch/x86/mm/p2m-ept.c +++ b/xen/arch/x86/mm/p2m-ept.c @@ -111,6 +111,7 @@ static void ept_p2m_type_to_flags(ept_en switch (access) { case p2m_access_n: + case p2m_access_n2rwx: entry->r = entry->w = entry->x = 0; break; case p2m_access_r: diff -r e315ce73f082 -r 66ca1a02082f xen/arch/x86/mm/p2m.c --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -1107,6 +1107,11 @@ bool_t p2m_mem_access_check(unsigned lon p2m_unlock(p2m); return 1; } + else if ( p2ma == p2m_access_n2rwx ) + { + ASSERT(access_w || access_r || access_x); + p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2mt, p2m_access_rwx); + } p2m_unlock(p2m); /* Otherwise, check if there is a memory event listener, and send the message along */ @@ -1124,10 +1129,13 @@ bool_t p2m_mem_access_check(unsigned lon } else { - /* A listener is not required, so clear the access restrictions */ - p2m_lock(p2m); - p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2mt, p2m_access_rwx); - p2m_unlock(p2m); + if ( p2ma != p2m_access_n2rwx ) + { + /* A listener is not required, so clear the access restrictions */ + p2m_lock(p2m); + p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2mt, p2m_access_rwx); + p2m_unlock(p2m); + } return 1; } @@ -1140,9 +1148,12 @@ bool_t p2m_mem_access_check(unsigned lon req.type = MEM_EVENT_TYPE_ACCESS; req.reason = MEM_EVENT_REASON_VIOLATION; - /* Pause the current VCPU unconditionally */ - vcpu_pause_nosync(v); - req.flags |= MEM_EVENT_FLAG_VCPU_PAUSED; + /* Pause the current VCPU */ + if ( p2ma != p2m_access_n2rwx ) + { + vcpu_pause_nosync(v); + req.flags |= MEM_EVENT_FLAG_VCPU_PAUSED; + } /* Send request to mem event */ req.gfn = gfn; @@ -1157,8 +1168,8 @@ bool_t p2m_mem_access_check(unsigned lon mem_event_put_request(d, &d->mem_event->access, &req); - /* VCPU paused, mem event request sent */ - return 0; + /* VCPU may be paused, return whether we promoted automatically */ + return (p2ma == p2m_access_n2rwx); } void p2m_mem_access_resume(struct domain *d) @@ -1204,6 +1215,7 @@ int p2m_set_mem_access(struct domain *d, p2m_access_wx, p2m_access_rwx, p2m_access_rx2rw, + p2m_access_n2rwx, p2m->default_access, }; diff -r e315ce73f082 -r 66ca1a02082f xen/include/asm-x86/p2m.h --- a/xen/include/asm-x86/p2m.h +++ b/xen/include/asm-x86/p2m.h @@ -108,6 +108,9 @@ typedef enum { p2m_access_wx = 6, p2m_access_rwx = 7, p2m_access_rx2rw = 8, /* Special: page goes from RX to RW on write */ + p2m_access_n2rwx = 9, /* Special: page goes from N to RWX on access, * + * generates an event but does not pause the + * vcpu */ /* NOTE: Assumed to be only 4 bits right now */ } p2m_access_t; diff -r e315ce73f082 -r 66ca1a02082f xen/include/public/hvm/hvm_op.h --- a/xen/include/public/hvm/hvm_op.h +++ b/xen/include/public/hvm/hvm_op.h @@ -174,6 +174,9 @@ typedef enum { HVMMEM_access_rwx, HVMMEM_access_rx2rw, /* Page starts off as r-x, but automatically * change to r-w on a write */ + HVMMEM_access_n2rwx, /* Log access: starts off as n, automatically + * goes to rwx, generating an event without + * pausing the vcpu */ HVMMEM_access_default /* Take the domain default */ } hvmmem_access_t; /* Notify that a region of memory is to have specific access types */ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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