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target-i386: defer VMEXIT to do_interrupt

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Paths through the softmmu code during code generation now need to be audited
to check for double locking of tb_lock. In particular, VMEXIT can take tb_lock
through cpu_vmexit -> cpu_x86_update_cr4 -> tlb_flush.

To avoid this, split VMEXIT delivery in two parts, similar to what is done with
exceptions. cpu_vmexit only records the VMEXIT exit code and information, and
cc->do_interrupt can then deliver it when it is safe to take the lock.

Backports commit 10cde894b63146139f981857e4eedf756fa53dcb from qemu
This commit is contained in:
Paolo Bonzini 2018-03-02 12:49:07 -05:00 committed by Lioncash
parent ad548f8110
commit bc7a9ccfbd
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GPG key ID: 4E3C3CC1031BA9C7
3 changed files with 25 additions and 18 deletions
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2
qemu/target/i386/cpu.h
View file

@ -695,6 +695,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
#define EXCP_SYSCALL 0x100 /* only happens in user only emulation
for syscall instruction */
#define EXCP_VMEXIT 0x100
/* i386-specific interrupt pending bits. */
#define CPU_INTERRUPT_POLL CPU_INTERRUPT_TGT_EXT_1
@ -1605,6 +1606,7 @@ void cpu_svm_check_intercept_param(CPUX86State *env1, uint32_t type,
uint64_t param, uintptr_t retaddr);
void cpu_vmexit(CPUX86State *nenv, uint32_t exit_code, uint64_t exit_info_1,
uintptr_t retaddr);
void do_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1);
/* seg_helper.c */
void do_interrupt_x86_hardirq(CPUX86State *env, int intno, int is_hw);

20
qemu/target/i386/seg_helper.c
View file

@ -1298,15 +1298,17 @@ void x86_cpu_do_interrupt(CPUState *cs)
/* successfully delivered */
env->old_exception = -1;
#else
/* simulate a real cpu exception. On i386, it can
trigger new exceptions, but we do not handle
double or triple faults yet. */
do_interrupt_all(cpu, cs->exception_index,
env->exception_is_int,
env->error_code,
env->exception_next_eip, 0);
/* successfully delivered */
env->old_exception = -1;
if (cs->exception_index >= EXCP_VMEXIT) {
assert(env->old_exception == -1);
do_vmexit(env, cs->exception_index - EXCP_VMEXIT, env->error_code);
} else {
do_interrupt_all(cpu, cs->exception_index,
env->exception_is_int,
env->error_code,
env->exception_next_eip, 0);
/* successfully delivered */
env->old_exception = -1;
}
#endif
}

21
qemu/target/i386/svm_helper.c
View file

@ -568,12 +568,10 @@ void helper_svm_check_io(CPUX86State *env, uint32_t port, uint32_t param,
}
}
/* Note: currently only 32 bits of exit_code are used */
void cpu_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1,
uintptr_t retaddr)
{
CPUState *cs = CPU(x86_env_get_cpu(env));
uint32_t int_ctl;
if (retaddr) {
cpu_restore_state(cs, retaddr);
@ -585,6 +583,18 @@ void cpu_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1,
x86_ldq_phys(cs, env->vm_vmcb + offsetof(struct vmcb,
control.exit_info_2)),
env->eip);
cs->exception_index = EXCP_VMEXIT + exit_code;
env->error_code = exit_info_1;
/* remove any pending exception */
env->old_exception = -1;
cpu_loop_exit(cs);
}
void do_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1)
{
CPUState *cs = CPU(x86_env_get_cpu(env));
uint32_t int_ctl;
if (env->hflags & HF_INHIBIT_IRQ_MASK) {
x86_stl_phys(cs,
@ -747,13 +757,6 @@ void cpu_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1,
/* If the host's rIP reloaded by #VMEXIT is outside the limit of the
host's code segment or non-canonical (in the case of long mode), a
#GP fault is delivered inside the host. */
/* remove any pending exception */
cs->exception_index = -1;
env->error_code = 0;
env->old_exception = -1;
cpu_loop_exit(cs);
}
#endif