From: Andres Lagar-Cavilla Date: Tue, 6 Dec 2011 21:16:56 +0000 (+0000) Subject: x86/mm: New mem access type to log access X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=acb4e3f39693c890267465ac9b9df30bad01e073;p=xen.git x86/mm: New mem access type to log access This patch adds a new p2m access type, n2rwx. It allows for implement a "log access" mode in the hypervisor, akin to log dirty but for all types of accesses. Faults caused by this access mode automatically promote the access rights of the offending p2m entry, place the event in the ring, and let the vcpu keep on executing. Signed-off-by: Andres Lagar-Cavilla Signed-off-by: Adin Scannell Acked-by: Tim Deegan Committed-by: Tim Deegan --- diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 0a63af88f2..901132d25e 100644 --- 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 long gpa, switch (p2ma) { case p2m_access_n: + case p2m_access_n2rwx: default: violation = access_r || access_w || access_x; break; diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c index c657a106d7..f31558e45c 100644 --- 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_entry_t *entry, p2m_type_t type, p2m_acces switch (access) { case p2m_access_n: + case p2m_access_n2rwx: entry->r = entry->w = entry->x = 0; break; case p2m_access_r: diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index fe93704549..d90c6deeba 100644 --- 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 long gpa, bool_t gla_valid, unsigned long g 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 long gpa, bool_t gla_valid, unsigned long g } 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 long gpa, bool_t gla_valid, unsigned long g 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 long gpa, bool_t gla_valid, unsigned long g 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, unsigned long start_pfn, p2m_access_wx, p2m_access_rwx, p2m_access_rx2rw, + p2m_access_n2rwx, p2m->default_access, }; diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h index 2e174bf184..8269144424 100644 --- 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 --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h index 1689cd22d6..6a78f757d5 100644 --- 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 */