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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] mem_event: Allow emulating an instruction that caused a page fault
This patch makes it possible to emulate an instruction that triggered
a page fault (received via the mem_event API). This is done by setting
the MEM_EVENT_FLAG_EMULATE in mem_event_response_t.flags. The purpose
of this is to be able to receive several distinct page fault mem_events
for the same address, and choose which ones are allowed to go through
from dom0 userspace.
Signed-off-by: Razvan Cojocaru <rzvncj@xxxxxxxxx>
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/arch/x86/hvm/hvm.c Mon Jan 14 16:31:29 2013 +0200
@@ -1293,7 +1293,8 @@ int hvm_hap_nested_page_fault(paddr_t gp
unsigned long gla,
bool_t access_r,
bool_t access_w,
- bool_t access_x)
+ bool_t access_x,
+ struct cpu_user_regs *regs)
{
unsigned long gfn = gpa >> PAGE_SHIFT;
p2m_type_t p2mt;
@@ -1386,7 +1387,7 @@ int hvm_hap_nested_page_fault(paddr_t gp
if ( violation )
{
if ( p2m_mem_access_check(gpa, gla_valid, gla, access_r,
- access_w, access_x, &req_ptr) )
+ access_w, access_x, &req_ptr, regs) )
{
fall_through = 1;
} else {
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/arch/x86/hvm/svm/svm.c Mon Jan 14 16:31:29 2013 +0200
@@ -1292,7 +1292,8 @@ static void svm_do_nested_pgfault(struct
ret = hvm_hap_nested_page_fault(gpa, 0, ~0ul,
1, /* All NPFs count as reads */
npfec & PFEC_write_access,
- npfec & PFEC_insn_fetch);
+ npfec & PFEC_insn_fetch,
+ regs);
if ( tb_init_done )
{
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/arch/x86/hvm/vmx/vmx.c Mon Jan 14 16:31:29 2013 +0200
@@ -2042,7 +2042,7 @@ static void vmx_wbinvd_intercept(void)
wbinvd();
}
-static void ept_handle_violation(unsigned long qualification, paddr_t gpa)
+static void ept_handle_violation(unsigned long qualification, paddr_t gpa,
struct cpu_user_regs *regs)
{
unsigned long gla, gfn = gpa >> PAGE_SHIFT;
mfn_t mfn;
@@ -2071,7 +2071,8 @@ static void ept_handle_violation(unsigne
? __vmread(GUEST_LINEAR_ADDRESS) : ~0ull,
qualification & EPT_READ_VIOLATION ? 1 : 0,
qualification & EPT_WRITE_VIOLATION ? 1 : 0,
- qualification & EPT_EXEC_VIOLATION ? 1 :
0) )
+ qualification & EPT_EXEC_VIOLATION ? 1 : 0,
+ regs) )
return;
/* Everything else is an error. */
@@ -2670,7 +2671,7 @@ void vmx_vmexit_handler(struct cpu_user_
{
paddr_t gpa = __vmread(GUEST_PHYSICAL_ADDRESS);
exit_qualification = __vmread(EXIT_QUALIFICATION);
- ept_handle_violation(exit_qualification, gpa);
+ ept_handle_violation(exit_qualification, gpa, regs);
break;
}
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/arch/x86/mm/p2m.c Mon Jan 14 16:31:29 2013 +0200
@@ -1205,7 +1205,7 @@ void p2m_mem_paging_resume(struct domain
bool_t p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
bool_t access_r, bool_t access_w, bool_t access_x,
- mem_event_request_t **req_ptr)
+ mem_event_request_t **req_ptr, struct cpu_user_regs
*regs)
{
struct vcpu *v = current;
unsigned long gfn = gpa >> PAGE_SHIFT;
@@ -1258,6 +1258,17 @@ bool_t p2m_mem_access_check(paddr_t gpa,
}
}
+ if ( v->arch.hvm_vmx.mem_event_emulate )
+ {
+ struct hvm_emulate_ctxt ctx[1] = {};
+
+ v->arch.hvm_vmx.mem_event_emulate = 0;
+ hvm_emulate_prepare(ctx, regs);
+ hvm_emulate_one(ctx);
+
+ return 1;
+ }
+
*req_ptr = NULL;
req = xzalloc(mem_event_request_t);
if ( req )
@@ -1296,8 +1307,15 @@ void p2m_mem_access_resume(struct domain
/* Pull all responses off the ring */
while( mem_event_get_response(d, &d->mem_event->access, &rsp) )
{
+ d->vcpu[rsp.vcpu_id]->arch.hvm_vmx.mem_event_emulate = 0;
+
if ( rsp.flags & MEM_EVENT_FLAG_DUMMY )
continue;
+
+ /* Mark vcpu for skipping one instruction upon rescheduling */
+ if ( rsp.flags & MEM_EVENT_FLAG_EMULATE )
+ d->vcpu[rsp.vcpu_id]->arch.hvm_vmx.mem_event_emulate = 1;
+
/* Unpause domain */
if ( rsp.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
vcpu_unpause(d->vcpu[rsp.vcpu_id]);
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/arch/x86/x86_64/asm-offsets.c
--- a/xen/arch/x86/x86_64/asm-offsets.c Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/arch/x86/x86_64/asm-offsets.c Mon Jan 14 16:31:29 2013 +0200
@@ -113,6 +113,7 @@ void __dummy__(void)
OFFSET(VCPU_vmx_emulate, struct vcpu, arch.hvm_vmx.vmx_emulate);
OFFSET(VCPU_vm86_seg_mask, struct vcpu, arch.hvm_vmx.vm86_segment_mask);
OFFSET(VCPU_hvm_guest_cr2, struct vcpu, arch.hvm_vcpu.guest_cr[2]);
+ OFFSET(VCPU_mem_event_emulate, struct vcpu,
arch.hvm_vmx.mem_event_emulate);
BLANK();
OFFSET(VCPU_nhvm_guestmode, struct vcpu, arch.hvm_vcpu.nvcpu.nv_guestmode);
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/include/asm-x86/hvm/hvm.h
--- a/xen/include/asm-x86/hvm/hvm.h Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/include/asm-x86/hvm/hvm.h Mon Jan 14 16:31:29 2013 +0200
@@ -433,7 +433,8 @@ int hvm_hap_nested_page_fault(paddr_t gp
bool_t gla_valid, unsigned long gla,
bool_t access_r,
bool_t access_w,
- bool_t access_x);
+ bool_t access_x,
+ struct cpu_user_regs *regs);
#define hvm_msr_tsc_aux(v) ({ \
struct domain *__d = (v)->domain; \
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/include/asm-x86/hvm/vmx/vmcs.h
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h Mon Jan 14 16:31:29 2013 +0200
@@ -124,6 +124,8 @@ struct arch_vmx_struct {
/* Remember EFLAGS while in virtual 8086 mode */
uint32_t vm86_saved_eflags;
int hostenv_migrated;
+ /* Should we emulate the first instruction on VCPU resume after a
mem_event? */
+ uint8_t mem_event_emulate;
};
int vmx_create_vmcs(struct vcpu *v);
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/include/asm-x86/p2m.h
--- a/xen/include/asm-x86/p2m.h Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/include/asm-x86/p2m.h Mon Jan 14 16:31:29 2013 +0200
@@ -566,7 +566,7 @@ void p2m_mem_paging_resume(struct domain
* locks -- caller must also xfree the request. */
bool_t p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
bool_t access_r, bool_t access_w, bool_t access_x,
- mem_event_request_t **req_ptr);
+ mem_event_request_t **req_ptr, struct cpu_user_regs
*regs);
/* Resumes the running of the VCPU, restarting the last instruction */
void p2m_mem_access_resume(struct domain *d);
diff -r 35a0556a7f76 -r a22fe4e2bc32 xen/include/public/mem_event.h
--- a/xen/include/public/mem_event.h Thu Jan 10 17:32:10 2013 +0000
+++ b/xen/include/public/mem_event.h Mon Jan 14 16:31:29 2013 +0200
@@ -36,6 +36,7 @@
#define MEM_EVENT_FLAG_EVICT_FAIL (1 << 2)
#define MEM_EVENT_FLAG_FOREIGN (1 << 3)
#define MEM_EVENT_FLAG_DUMMY (1 << 4)
+#define MEM_EVENT_FLAG_EMULATE (1 << 5)
/* Reasons for the memory event request */
#define MEM_EVENT_REASON_UNKNOWN 0 /* typical reason */
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