[PATCH 4.9 24/31] KVM: x86: add tracepoints around __direct_map and FNAME(fetch)

Greg Kroah-Hartman
2019-11-15T06:22:53Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit 335e192a3fa415e1202c8b9ecdaaecd643f823cc upstream.

These are useful in debugging shadow paging.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 4.9:
- Keep using PT_PRESENT_MASK to test page write permission
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/mmu.c | 13 ++++-----
arch/x86/kvm/mmutrace.h | 59 +++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/paging_tmpl.h | 2 +
3 files changed, 67 insertions(+), 7 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -131,9 +131,6 @@ module_param(dbg, bool, 0644);

#include <trace/events/kvm.h>

-#define CREATE_TRACE_POINTS
-#include "mmutrace.h"
-
#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))

@@ -193,8 +190,12 @@ static u64 __read_mostly shadow_mmio_mas
static u64 __read_mostly shadow_present_mask;

static void mmu_spte_set(u64 *sptep, u64 spte);
+static bool is_executable_pte(u64 spte);
static void mmu_free_roots(struct kvm_vcpu *vcpu);

+#define CREATE_TRACE_POINTS
+#include "mmutrace.h"
+
void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask)
{
shadow_mmio_mask = mmio_mask;
@@ -2667,10 +2668,7 @@ static int mmu_set_spte(struct kvm_vcpu
ret = RET_PF_EMULATE;

pgprintk("%s: setting spte %llx\n", __func__, *sptep);
- pgprintk("instantiating %s PTE (%s) at %llx (%llx) addr %p\n",
- is_large_pte(*sptep)? "2MB" : "4kB",
- *sptep & PT_PRESENT_MASK ?"RW":"R", gfn,
- *sptep, sptep);
+ trace_kvm_mmu_set_spte(level, gfn, sptep);
if (!was_rmapped && is_large_pte(*sptep))
++vcpu->kvm->stat.lpages;

@@ -2781,6 +2779,7 @@ static int __direct_map(struct kvm_vcpu
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return RET_PF_RETRY;

+ trace_kvm_mmu_spte_requested(gpa, level, pfn);
for_each_shadow_entry(vcpu, gpa, it) {
base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
if (it.level == level)
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -322,6 +322,65 @@ TRACE_EVENT(
__entry->kvm_gen == __entry->spte_gen
)
);
+
+TRACE_EVENT(
+ kvm_mmu_set_spte,
+ TP_PROTO(int level, gfn_t gfn, u64 *sptep),
+ TP_ARGS(level, gfn, sptep),
+
+ TP_STRUCT__entry(
+ __field(u64, gfn)
+ __field(u64, spte)
+ __field(u64, sptep)
+ __field(u8, level)
+ /* These depend on page entry type, so compute them now. */
+ __field(bool, r)
+ __field(bool, x)
+ __field(u8, u)
+ ),
+
+ TP_fast_assign(
+ __entry->gfn = gfn;
+ __entry->spte = *sptep;
+ __entry->sptep = virt_to_phys(sptep);
+ __entry->level = level;
+ __entry->r = shadow_present_mask || (__entry->spte & PT_PRESENT_MASK);
+ __entry->x = is_executable_pte(__entry->spte);
+ __entry->u = shadow_user_mask ? !!(__entry->spte & shadow_user_mask) : -1;
+ ),
+
+ TP_printk("gfn %llx spte %llx (%s%s%s%s) level %d at %llx",
+ __entry->gfn, __entry->spte,
+ __entry->r ? "r" : "-",
+ __entry->spte & PT_PRESENT_MASK ? "w" : "-",
+ __entry->x ? "x" : "-",
+ __entry->u == -1 ? "" : (__entry->u ? "u" : "-"),
+ __entry->level, __entry->sptep
+ )
+);
+
+TRACE_EVENT(
+ kvm_mmu_spte_requested,
+ TP_PROTO(gpa_t addr, int level, kvm_pfn_t pfn),
+ TP_ARGS(addr, level, pfn),
+
+ TP_STRUCT__entry(
+ __field(u64, gfn)
+ __field(u64, pfn)
+ __field(u8, level)
+ ),
+
+ TP_fast_assign(
+ __entry->gfn = addr >> PAGE_SHIFT;
+ __entry->pfn = pfn | (__entry->gfn & (KVM_PAGES_PER_HPAGE(level) - 1));
+ __entry->level = level;
+ ),
+
+ TP_printk("gfn %llx pfn %llx level %d",
+ __entry->gfn, __entry->pfn, __entry->level
+ )
+);
+
#endif /* _TRACE_KVMMMU_H */

#undef TRACE_INCLUDE_PATH
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -626,6 +626,8 @@ static int FNAME(fetch)(struct kvm_vcpu

base_gfn = gw->gfn;

+ trace_kvm_mmu_spte_requested(addr, gw->level, pfn);
+
for (; shadow_walk_okay(&it); shadow_walk_next(&it)) {
clear_sp_write_flooding_count(it.sptep);
base_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);