[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [qemu-xen master] cputlb: ensure we save the IOTLB data in case of reset
commit 2f3a57ee47df970d19fa5b324d44aab857d43517 Author: Alex Bennée <alex.bennee@xxxxxxxxxx> AuthorDate: Mon Jul 13 21:04:10 2020 +0100 Commit: Alex Bennée <alex.bennee@xxxxxxxxxx> CommitDate: Wed Jul 15 11:52:43 2020 +0100 cputlb: ensure we save the IOTLB data in case of reset Any write to a device might cause a re-arrangement of memory triggering a TLB flush and potential re-size of the TLB invalidating previous entries. This would cause users of qemu_plugin_get_hwaddr() to see the warning: invalid use of qemu_plugin_get_hwaddr because of the failed tlb_lookup which should always succeed. To prevent this we save the IOTLB data in case it is later needed by a plugin doing a lookup. Signed-off-by: Alex Bennée <alex.bennee@xxxxxxxxxx> Reviewed-by: Richard Henderson <richard.henderson@xxxxxxxxxx> Message-Id: <20200713200415.26214-7-alex.bennee@xxxxxxxxxx> --- accel/tcg/cputlb.c | 38 +++++++++++++++++++++++++++++++++++--- include/hw/core/cpu.h | 16 ++++++++++++++++ include/qemu/typedefs.h | 1 + 3 files changed, 52 insertions(+), 3 deletions(-) diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c index 1e815357c7..d370aedb47 100644 --- a/accel/tcg/cputlb.c +++ b/accel/tcg/cputlb.c @@ -1073,6 +1073,24 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry, return val; } +/* + * Save a potentially trashed IOTLB entry for later lookup by plugin. + * + * We also need to track the thread storage address because the RCU + * cleanup that runs when we leave the critical region (the current + * execution) is actually in a different thread. + */ +static void save_iotlb_data(CPUState *cs, hwaddr addr, + MemoryRegionSection *section, hwaddr mr_offset) +{ +#ifdef CONFIG_PLUGIN + SavedIOTLB *saved = &cs->saved_iotlb; + saved->addr = addr; + saved->section = section; + saved->mr_offset = mr_offset; +#endif +} + static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry, int mmu_idx, uint64_t val, target_ulong addr, uintptr_t retaddr, MemOp op) @@ -1092,6 +1110,12 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry, } cpu->mem_io_pc = retaddr; + /* + * The memory_region_dispatch may trigger a flush/resize + * so for plugins we save the iotlb_data just in case. + */ + save_iotlb_data(cpu, iotlbentry->addr, section, mr_offset); + if (mr->global_locking && !qemu_mutex_iothread_locked()) { qemu_mutex_lock_iothread(); locked = true; @@ -1381,8 +1405,11 @@ void *tlb_vaddr_to_host(CPUArchState *env, abi_ptr addr, * in the softmmu lookup code (or helper). We don't handle re-fills or * checking the victim table. This is purely informational. * - * This should never fail as the memory access being instrumented - * should have just filled the TLB. + * This almost never fails as the memory access being instrumented + * should have just filled the TLB. The one corner case is io_writex + * which can cause TLB flushes and potential resizing of the TLBs + * loosing the information we need. In those cases we need to recover + * data from a copy of the io_tlb entry. */ bool tlb_plugin_lookup(CPUState *cpu, target_ulong addr, int mmu_idx, @@ -1406,8 +1433,13 @@ bool tlb_plugin_lookup(CPUState *cpu, target_ulong addr, int mmu_idx, data->v.ram.hostaddr = addr + tlbe->addend; } return true; + } else { + SavedIOTLB *saved = &cpu->saved_iotlb; + data->is_io = true; + data->v.io.section = saved->section; + data->v.io.offset = saved->mr_offset; + return true; } - return false; } #endif diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 5542577d2b..8f145733ce 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -259,6 +259,18 @@ struct CPUWatchpoint { QTAILQ_ENTRY(CPUWatchpoint) entry; }; +#ifdef CONFIG_PLUGIN +/* + * For plugins we sometime need to save the resolved iotlb data before + * the memory regions get moved around by io_writex. + */ +typedef struct SavedIOTLB { + hwaddr addr; + MemoryRegionSection *section; + hwaddr mr_offset; +} SavedIOTLB; +#endif + struct KVMState; struct kvm_run; @@ -417,7 +429,11 @@ struct CPUState { DECLARE_BITMAP(plugin_mask, QEMU_PLUGIN_EV_MAX); +#ifdef CONFIG_PLUGIN GArray *plugin_mem_cbs; + /* saved iotlb data from io_writex */ + SavedIOTLB saved_iotlb; +#endif /* TODO Move common fields from CPUArchState here. */ int cpu_index; diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h index 15f5047bf1..427027a970 100644 --- a/include/qemu/typedefs.h +++ b/include/qemu/typedefs.h @@ -116,6 +116,7 @@ typedef struct QObject QObject; typedef struct QString QString; typedef struct RAMBlock RAMBlock; typedef struct Range Range; +typedef struct SavedIOTLB SavedIOTLB; typedef struct SHPCDevice SHPCDevice; typedef struct SSIBus SSIBus; typedef struct VirtIODevice VirtIODevice; -- generated by git-patchbot for /home/xen/git/qemu-xen.git#master
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