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Disable global interrupts early so all the software state maintained by bhyve

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is sampled "atomically". Any interrupts after this point will be held pending
by the CPU until the guest starts executing and will immediately trigger a
#VMEXIT.

Reviewed by:	Anish Gupta (akgupt3@gmail.com)
This commit is contained in:
Neel Natu 2014-06-11 17:48:07 +00:00
parent 3787148758
commit 4e98fc9011
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/bhyve_svm/; revision=267367
1 changed files with 30 additions and 25 deletions
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55
sys/amd64/vmm/amd/svm.c
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@ -1156,22 +1156,24 @@ svm_vmrun(void *arg, int vcpu, register_t rip, pmap_t pmap,
do { do {
vmexit->inst_length = 0; vmexit->inst_length = 0;
/* We are asked to give the cpu by scheduler. */
if (curthread->td_flags & (TDF_ASTPENDING | TDF_NEEDRESCHED)) { /*
vmexit->exitcode = VM_EXITCODE_BOGUS; * Disable global interrupts to guarantee atomicity during
vmm_stat_incr(vm, vcpu, VMEXIT_ASTPENDING, 1); * loading of guest state. This includes not only the state
VCPU_CTR1(vm, vcpu, * loaded by the "vmrun" instruction but also software state
"SVM: ASTPENDING, RIP:0x%lx\n", state->rip); * maintained by the hypervisor: suspended and rendezvous
vmexit->rip = state->rip; * state, NPT generation number, vlapic interrupts etc.
break; */
} disable_gintr();
if (vcpu_suspended(suspended_cookie)) { if (vcpu_suspended(suspended_cookie)) {
enable_gintr();
vm_exit_suspended(vm, vcpu, state->rip); vm_exit_suspended(vm, vcpu, state->rip);
break; break;
} }
if (vcpu_rendezvous_pending(rend_cookie)) { if (vcpu_rendezvous_pending(rend_cookie)) {
enable_gintr();
vmexit->exitcode = VM_EXITCODE_RENDEZVOUS; vmexit->exitcode = VM_EXITCODE_RENDEZVOUS;
vmm_stat_incr(vm, vcpu, VMEXIT_RENDEZVOUS, 1); vmm_stat_incr(vm, vcpu, VMEXIT_RENDEZVOUS, 1);
VCPU_CTR1(vm, vcpu, VCPU_CTR1(vm, vcpu,
@ -1181,32 +1183,36 @@ svm_vmrun(void *arg, int vcpu, register_t rip, pmap_t pmap,
break; break;
} }
/* We are asked to give the cpu by scheduler. */
if (curthread->td_flags & (TDF_ASTPENDING | TDF_NEEDRESCHED)) {
enable_gintr();
vmexit->exitcode = VM_EXITCODE_BOGUS;
vmm_stat_incr(vm, vcpu, VMEXIT_ASTPENDING, 1);
VCPU_CTR1(vm, vcpu,
"SVM: ASTPENDING, RIP:0x%lx\n", state->rip);
vmexit->rip = state->rip;
break;
}
(void)svm_set_vmcb(svm_get_vmcb(svm_sc, vcpu), svm_sc->asid); (void)svm_set_vmcb(svm_get_vmcb(svm_sc, vcpu), svm_sc->asid);
svm_handle_exitintinfo(svm_sc, vcpu); svm_handle_exitintinfo(svm_sc, vcpu);
(void)svm_inj_interrupts(svm_sc, vcpu, vlapic); (void)svm_inj_interrupts(svm_sc, vcpu, vlapic);
/* Change TSS type to available.*/ /* Change TSS type to available.*/
setup_tss_type(); setup_tss_type();
/*
* Disable global interrupt to guarantee atomicity
* during loading of guest state.
* See 15.5.1 "Loading guest state" APM2.
*/
disable_gintr();
/* Launch Virtual Machine. */ /* Launch Virtual Machine. */
svm_launch(vmcb_pa, gctx, hctx); svm_launch(vmcb_pa, gctx, hctx);
/* /*
* Only GDTR and IDTR of host is saved and restore by SVM, * Only GDTR and IDTR of host is saved and restore by SVM,
* LDTR and TR need to be restored by VMM. * LDTR and TR need to be restored by VMM.
* XXX: kernel doesn't use LDT, only user space. * XXX: kernel doesn't use LDT, only user space.
*/ */
ltr(GSEL(GPROC0_SEL, SEL_KPL)); ltr(GSEL(GPROC0_SEL, SEL_KPL));
/* /*
* Guest FS and GS selector are stashed by vmload and vmsave. * Guest FS and GS selector are stashed by vmload and vmsave.
* Host FS and GS selector are stashed by svm_launch(). * Host FS and GS selector are stashed by svm_launch().
@ -1220,15 +1226,14 @@ svm_vmrun(void *arg, int vcpu, register_t rip, pmap_t pmap,
*/ */
wrmsr(MSR_GSBASE, (uint64_t)&__pcpu[vcpustate->lastcpu]); wrmsr(MSR_GSBASE, (uint64_t)&__pcpu[vcpustate->lastcpu]);
wrmsr(MSR_KGSBASE, (uint64_t)&__pcpu[vcpustate->lastcpu]); wrmsr(MSR_KGSBASE, (uint64_t)&__pcpu[vcpustate->lastcpu]);
/* vcpu exit with glbal interrupt disabled. */ /* #VMEXIT disables interrupts so re-enable them here. */
enable_gintr(); enable_gintr();
/* Handle #VMEXIT and if required return to user space. */ /* Handle #VMEXIT and if required return to user space. */
loop = svm_vmexit(svm_sc, vcpu, vmexit); loop = svm_vmexit(svm_sc, vcpu, vmexit);
vcpustate->loop++; vcpustate->loop++;
vmm_stat_incr(vm, vcpu, VMEXIT_COUNT, 1); vmm_stat_incr(vm, vcpu, VMEXIT_COUNT, 1);
} while (loop); } while (loop);
return (0); return (0);