[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v3 1/2] x86/mem_sharing: make fork_reset more configurable
Allow 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> --- v3: Rebase on simpler approach after dropping empty_p2m feature v2: address review comments and add more sanity checking --- tools/include/xenctrl.h | 3 ++- tools/libs/ctrl/xc_memshr.c | 7 ++++++- xen/arch/x86/include/asm/mem_sharing.h | 9 +++++++++ xen/arch/x86/mm/mem_sharing.c | 24 +++++++++++++++++++----- xen/common/vm_event.c | 15 +++++++++++++++ xen/include/public/memory.h | 4 +++- xen/include/public/vm_event.h | 8 ++++++++ 7 files changed, 62 insertions(+), 8 deletions(-) diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h index 95bd5eca67..1b089a2c02 100644 --- a/tools/include/xenctrl.h +++ b/tools/include/xenctrl.h @@ -2290,7 +2290,8 @@ int xc_memshr_fork(xc_interface *xch, * * With VMs that have a lot of memory this call may block for a long time. */ -int xc_memshr_fork_reset(xc_interface *xch, uint32_t forked_domain); +int xc_memshr_fork_reset(xc_interface *xch, uint32_t forked_domain, + bool reset_state, bool reset_memory); /* Debug calls: return the number of pages referencing the shared frame backing * the input argument. Should be one or greater. diff --git a/tools/libs/ctrl/xc_memshr.c b/tools/libs/ctrl/xc_memshr.c index a6cfd7dccf..a0d0b894e2 100644 --- a/tools/libs/ctrl/xc_memshr.c +++ b/tools/libs/ctrl/xc_memshr.c @@ -257,12 +257,17 @@ int xc_memshr_fork(xc_interface *xch, uint32_t pdomid, uint32_t domid, return xc_memshr_memop(xch, domid, &mso); } -int xc_memshr_fork_reset(xc_interface *xch, uint32_t domid) +int xc_memshr_fork_reset(xc_interface *xch, uint32_t domid, bool reset_state, + bool reset_memory) { xen_mem_sharing_op_t mso; memset(&mso, 0, sizeof(mso)); mso.op = XENMEM_sharing_op_fork_reset; + if ( reset_state ) + mso.u.fork.flags |= XENMEM_FORK_RESET_STATE; + if ( reset_memory ) + mso.u.fork.flags |= XENMEM_FORK_RESET_MEMORY; return xc_memshr_memop(xch, domid, &mso); } 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 15e6a7ed81..2f447d94ab 100644 --- a/xen/arch/x86/mm/mem_sharing.c +++ b/xen/arch/x86/mm/mem_sharing.c @@ -1879,15 +1879,21 @@ 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) @@ -1920,7 +1926,9 @@ 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); @@ -2227,15 +2235,21 @@ 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..d26a6699fc 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 +399,16 @@ 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 ) + ASSERT(!mem_sharing_fork_reset(d, reset_state, reset_mem)); + } +#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..81c2ee28cc 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 entried from physmap (if VM is fork) + */ +#define VM_EVENT_FLAG_RESET_FORK_MEMORY (1 << 15) /* * Reasons for the vm event request -- 2.25.1
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