Xen project Mailing List

On Thu, Aug 7, 2014 at 11:39 PM, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:

On 08/07/2014 03:47 PM, Tamas K Lengyel wrote:

On Intel EPT the exit qualification generated by a violation also includes a bit (EPT_GLA_FAULT) which describes the following information:
Set if the access causing the EPT violation is to a guest-physical address that is the translation of a linear address. Clear if the access causing the EPT violation is to a paging-structure entry as part of a page walk or the update of an accessed or dirty bit.

For more information see Table 27-7 in the Intel SDM.

This patch extends the mem_event system to deliver this extra information, which could be useful for determining the cause of a violation.

v2: Split gla_fault into fault_in_gpt and fault_gla to be more compatible with the AMD implementation.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
---
xen/arch/x86/hvm/hvm.c | 8 ++++++--
xen/arch/x86/hvm/svm/svm.c | 2 +-
xen/arch/x86/hvm/vmx/vmx.c | 23 ++++++++++++++++++++++-
xen/arch/x86/mm/p2m.c | 5 ++++-
xen/include/asm-x86/hvm/hvm.h | 5 ++++-
xen/include/asm-x86/p2m.h | 3 ++-
xen/include/public/mem_event.h | 4 +++-
7 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index e834406..d7b5e2b 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2725,6 +2725,8 @@ void hvm_inject_page_fault(int errcode, unsigned long cr2)
int hvm_hap_nested_page_fault(paddr_t gpa,
bool_t gla_valid,
unsigned long gla,
+ bool_t fault_in_gpt,
+ bool_t fault_gla,
bool_t access_r,
bool_t access_w,
bool_t access_x)
@@ -2832,8 +2834,10 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
if ( violation )
{
- if ( p2m_mem_access_check(gpa, gla_valid, gla, access_r,
- access_w, access_x, &req_ptr) )
+ if ( p2m_mem_access_check(gpa, gla_valid, gla,
+ fault_in_gpt, fault_gla,
+ access_r, access_w, access_x,
+ &req_ptr) )
{
fall_through = 1;
} else {
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 76616ac..9e35e7a 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1403,7 +1403,7 @@ static void svm_do_nested_pgfault(struct vcpu *v,
p2m_access_t p2ma;
struct p2m_domain *p2m = NULL;
- ret = hvm_hap_nested_page_fault(gpa, 0, ~0ul,
+ ret = hvm_hap_nested_page_fault(gpa, 0, ~0ul, 0, 0,

Why not pass the actual bits that the HW provides?

The actual bits could be passed but it makes no difference at this point since the AMD side isn't setup to work with mem_event. When it is integrated, those bits could and should be passed accordingly.

Tamas

-boris

1, /* All NPFs count as reads */
npfec & PFEC_write_access,
npfec & PFEC_insn_fetch);
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 2caa04a..7ebf289 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2353,6 +2353,7 @@ static void ept_handle_violation(unsigned long qualification, paddr_t gpa)
p2m_type_t p2mt;
int ret;
struct domain *d = current->domain;
+ bool_t fault_in_gpt, fault_gla;
if ( tb_init_done )
{
@@ -2371,11 +2372,31 @@ static void ept_handle_violation(unsigned long qualification, paddr_t gpa)
}
if ( qualification & EPT_GLA_VALID )
+ {
__vmread(GUEST_LINEAR_ADDRESS, &gla);
+
+ if ( qualification & EPT_GLA_FAULT )
+ {
+ fault_in_gpt = 0;
+ fault_gla = 1;
+ }
+ else
+ {
+ fault_in_gpt = 1;
+ fault_gla = 0;
+ }
+ }
else
+ {
gla = ~0ull;
+ fault_in_gpt = 0;
+ fault_gla = 0;
+ }
ret = hvm_hap_nested_page_fault(gpa,
- !!(qualification & EPT_GLA_VALID), gla,
+ !!(qualification & EPT_GLA_VALID),
+ gla,
+ fault_in_gpt,
+ fault_gla,
!!(qualification & EPT_READ_VIOLATION),
!!(qualification & EPT_WRITE_VIOLATION),
!!(qualification & EPT_EXEC_VIOLATION));
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index bca9f0f..132f0d2 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1323,7 +1323,8 @@ void p2m_mem_paging_resume(struct domain *d)
}
}
-bool_t p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
+bool_t p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
+ bool_t fault_in_gpt, bool_t fault_gla,
bool_t access_r, bool_t access_w, bool_t access_x,
mem_event_request_t **req_ptr)
{
@@ -1405,6 +1406,8 @@ bool_t p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
req->offset = gpa & ((1 << PAGE_SHIFT) - 1);
req->gla_valid = gla_valid;
req->gla = gla;
+ req->fault_in_gpt = fault_in_gpt;
+ req->fault_gla = fault_gla;
req->access_r = access_r;
req->access_w = access_w;
req->access_x = access_x;
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 0ebd478..de755b6 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -456,7 +456,10 @@ static inline void hvm_invalidate_regs_fields(struct cpu_user_regs *regs)
}
int hvm_hap_nested_page_fault(paddr_t gpa,
- bool_t gla_valid, unsigned long gla,
+ bool_t gla_valid,
+ unsigned long gla,
+ bool_t fault_in_gpt,
+ bool_t fault_gla,
bool_t access_r,
bool_t access_w,
bool_t access_x);
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 0ddbadb..59803c5 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -597,7 +597,8 @@ void p2m_mem_paging_resume(struct domain *d);
* been promoted with no underlying vcpu pause. If the req_ptr has been populated,
* then the caller must put the event in the ring (once having released get_gfn*
* 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 p2m_mem_access_check(paddr_t gpa, bool_t gla_valid, unsigned long gla,
+ bool_t fault_in_gpt, bool_t fault_gla,
bool_t access_r, bool_t access_w, bool_t access_x,
mem_event_request_t **req_ptr);
/* Resumes the running of the VCPU, restarting the last instruction */
diff --git a/xen/include/public/mem_event.h b/xen/include/public/mem_event.h
index 3831b41..1ba6863 100644
--- a/xen/include/public/mem_event.h
+++ b/xen/include/public/mem_event.h
@@ -62,7 +62,9 @@ typedef struct mem_event_st {
uint16_t access_w:1;
uint16_t access_x:1;
uint16_t gla_valid:1;
- uint16_t available:12;
+ uint16_t fault_in_gpt:1;
+ uint16_t fault_gla:1;
+ uint16_t available:10;
uint16_t reason;
} mem_event_request_t, mem_event_response_t;

Re: [Xen-devel] [PATCH v2 1/2] x86/mem_event: Deliver gla fault EPT violation information