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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] x86/mem_sharing: make fork_reset more configurable
commit d711a8e5279d830d2e4f0f55246ed0c6e4a6bbed
Author: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
AuthorDate: Thu Apr 28 16:15:33 2022 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Apr 28 16:15:33 2022 +0200
x86/mem_sharing: make fork_reset more configurable
Alow specify distinct parts of the fork VM to be reset. This is useful when
a
fuzzing operation involves mapping in only a handful of pages that are known
ahead of time. Throwing these pages away just to be re-copied immediately is
expensive, thus allowing to specify partial resets can speed things up.
Also allow resetting to be initiated from vm_event responses as an
optiomization.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
xen/arch/x86/include/asm/mem_sharing.h | 9 +++++++++
xen/arch/x86/mm/mem_sharing.c | 24 +++++++++++++++++++-----
xen/common/vm_event.c | 16 ++++++++++++++++
xen/include/public/memory.h | 4 +++-
xen/include/public/vm_event.h | 8 ++++++++
5 files changed, 55 insertions(+), 6 deletions(-)
diff --git a/xen/arch/x86/include/asm/mem_sharing.h
b/xen/arch/x86/include/asm/mem_sharing.h
index cf7a12f4d2..2c00069bc9 100644
--- a/xen/arch/x86/include/asm/mem_sharing.h
+++ b/xen/arch/x86/include/asm/mem_sharing.h
@@ -85,6 +85,9 @@ static inline bool mem_sharing_is_fork(const struct domain *d)
int mem_sharing_fork_page(struct domain *d, gfn_t gfn,
bool unsharing);
+int mem_sharing_fork_reset(struct domain *d, bool reset_state,
+ bool reset_memory);
+
/*
* If called by a foreign domain, possible errors are
* -EBUSY -> ring full
@@ -148,6 +151,12 @@ static inline int mem_sharing_fork_page(struct domain *d,
gfn_t gfn, bool lock)
return -EOPNOTSUPP;
}
+static inline int mem_sharing_fork_reset(struct domain *d, bool reset_state,
+ bool reset_memory)
+{
+ return -EOPNOTSUPP;
+}
+
#endif
#endif /* __MEM_SHARING_H__ */
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 61538c3fb2..8f9d9ed9a9 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1891,15 +1891,21 @@ static int fork(struct domain *cd, struct domain *d)
* footprints the hypercall continuation should be implemented (or if this
* feature needs to be become "stable").
*/
-static int mem_sharing_fork_reset(struct domain *d)
+int mem_sharing_fork_reset(struct domain *d, bool reset_state,
+ bool reset_memory)
{
- int rc;
+ int rc = 0;
struct domain *pd = d->parent;
struct p2m_domain *p2m = p2m_get_hostp2m(d);
struct page_info *page, *tmp;
+ ASSERT(reset_state || reset_memory);
+
domain_pause(d);
+ if ( !reset_memory )
+ goto state;
+
/* need recursive lock because we will free pages */
spin_lock_recursive(&d->page_alloc_lock);
page_list_for_each_safe(page, tmp, &d->page_list)
@@ -1932,7 +1938,9 @@ static int mem_sharing_fork_reset(struct domain *d)
}
spin_unlock_recursive(&d->page_alloc_lock);
- rc = copy_settings(d, pd);
+ state:
+ if ( reset_state )
+ rc = copy_settings(d, pd);
domain_unpause(d);
@@ -2239,15 +2247,21 @@ int
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
case XENMEM_sharing_op_fork_reset:
{
+ bool reset_state = mso.u.fork.flags & XENMEM_FORK_RESET_STATE;
+ bool reset_memory = mso.u.fork.flags & XENMEM_FORK_RESET_MEMORY;
+
rc = -EINVAL;
- if ( mso.u.fork.pad || mso.u.fork.flags )
+ if ( mso.u.fork.pad || (!reset_state && !reset_memory) )
+ goto out;
+ if ( mso.u.fork.flags &
+ ~(XENMEM_FORK_RESET_STATE | XENMEM_FORK_RESET_MEMORY) )
goto out;
rc = -ENOSYS;
if ( !d->parent )
goto out;
- rc = mem_sharing_fork_reset(d);
+ rc = mem_sharing_fork_reset(d, reset_state, reset_memory);
break;
}
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 84cf52636b..4a8f02893e 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -28,6 +28,11 @@
#include <asm/p2m.h>
#include <asm/monitor.h>
#include <asm/vm_event.h>
+
+#ifdef CONFIG_MEM_SHARING
+#include <asm/mem_sharing.h>
+#endif
+
#include <xsm/xsm.h>
#include <public/hvm/params.h>
@@ -394,6 +399,17 @@ static int vm_event_resume(struct domain *d, struct
vm_event_domain *ved)
if ( rsp.reason == VM_EVENT_REASON_MEM_PAGING )
p2m_mem_paging_resume(d, &rsp);
#endif
+#ifdef CONFIG_MEM_SHARING
+ if ( mem_sharing_is_fork(d) )
+ {
+ bool reset_state = rsp.flags & VM_EVENT_FLAG_RESET_FORK_STATE;
+ bool reset_mem = rsp.flags & VM_EVENT_FLAG_RESET_FORK_MEMORY;
+
+ if ( (reset_state || reset_mem) &&
+ mem_sharing_fork_reset(d, reset_state, reset_mem) )
+ ASSERT_UNREACHABLE();
+ }
+#endif
/*
* Check emulation flags in the arch-specific handler only, as it
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index a1a0f0233a..f8d26fb77d 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -541,12 +541,14 @@ struct xen_mem_sharing_op {
uint32_t gref; /* IN: gref to debug */
} u;
} debug;
- struct mem_sharing_op_fork { /* OP_FORK */
+ struct mem_sharing_op_fork { /* OP_FORK{,_RESET} */
domid_t parent_domain; /* IN: parent's domain id */
/* Only makes sense for short-lived forks */
#define XENMEM_FORK_WITH_IOMMU_ALLOWED (1u << 0)
/* Only makes sense for short-lived forks */
#define XENMEM_FORK_BLOCK_INTERRUPTS (1u << 1)
+#define XENMEM_FORK_RESET_STATE (1u << 2)
+#define XENMEM_FORK_RESET_MEMORY (1u << 3)
uint16_t flags; /* IN: optional settings */
uint32_t pad; /* Must be set to 0 */
} fork;
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index bb003d21d0..1673bb8703 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -127,6 +127,14 @@
* Reset the vmtrace buffer (if vmtrace is enabled)
*/
#define VM_EVENT_FLAG_RESET_VMTRACE (1 << 13)
+/*
+ * Reset the VM state (if VM is fork)
+ */
+#define VM_EVENT_FLAG_RESET_FORK_STATE (1 << 14)
+/*
+ * Remove unshared entries from physmap (if VM is fork)
+ */
+#define VM_EVENT_FLAG_RESET_FORK_MEMORY (1 << 15)
/*
* Reasons for the vm event request
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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