Until this patch we bounced between the VM and the VMM for a couple of
instructions after CLGI, only to find out that yet another SVM instruction
follows.
Since roundtrips are really expensive, it's a lot faster to emulate these
few instructions. Now we can execute CLGI/VMLOAD/VMRUN on one intercept and
VMEXIT/VMSAVE on another. This is a major speed improvement!
(introduced in v6, optional)
Signed-off-by: Alexander Graf <[EMAIL PROTECTED]>
---
arch/x86/kvm/svm.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 69 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 83332d7..e246104 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -79,6 +79,11 @@ static int nested_svm_vmsave(struct vcpu_svm *svm, void
*nested_vmcb,
void *arg2, void *opaque);
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
+static int vmload_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run);
+static int vmsave_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run);
+static int vmrun_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run);
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run);
+
static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
{
@@ -1456,6 +1461,50 @@ static int nested_svm_exit_handled(struct vcpu_svm *svm,
bool kvm_override)
nested_svm_exit_handled_real);
}
+static int nested_svm_emulate(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+ int er;
+ u32 opcode = 0;
+ unsigned long rip;
+ unsigned long rip_linear;
+
+ svm->vmcb->save.rax = svm->vcpu.arch.regs[VCPU_REGS_RAX];
+ svm->vmcb->save.rsp = svm->vcpu.arch.regs[VCPU_REGS_RSP];
+ svm->vmcb->save.rip = svm->vcpu.arch.regs[VCPU_REGS_RIP];
+ rip = svm->vcpu.arch.regs[VCPU_REGS_RIP];
+ rip_linear = rip + svm_seg(&svm->vcpu, VCPU_SREG_CS)->base;
+
+ er = emulator_read_std(rip_linear, (void *)&opcode, 3, &svm->vcpu);
+ if (er != X86EMUL_CONTINUE)
+ return er;
+ er = EMULATE_FAIL;
+
+ switch (opcode) {
+ case 0xda010f:
+ vmload_interception(svm, kvm_run);
+ er = EMULATE_DONE;
+ break;
+ case 0xd8010f:
+ vmrun_interception(svm, kvm_run);
+ er = EMULATE_DONE;
+ break;
+ case 0xdb010f:
+ vmsave_interception(svm, kvm_run);
+ er = EMULATE_DONE;
+ break;
+ case 0xdc010f:
+ stgi_interception(svm, kvm_run);
+ er = EMULATE_DONE;
+ break;
+ default:
+ nsvm_printk("NSVM: Opcode %x unknown\n", opcode);
+ }
+
+ nsvm_printk("NSVM: svm emul at 0x%lx -> %d\n", rip, er);
+
+ return er;
+}
+
static int nested_svm_vmexit_real(struct vcpu_svm *svm, void *arg1,
void *arg2, void *opaque)
{
@@ -1551,6 +1600,9 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
kvm_mmu_reset_context(&svm->vcpu);
kvm_mmu_load(&svm->vcpu);
+ /* KVM calls vmsave after vmrun, so let's run it now if we can */
+ nested_svm_emulate(svm, NULL);
+
return 0;
}
@@ -1773,6 +1825,23 @@ static int clgi_interception(struct vcpu_svm *svm,
struct kvm_run *kvm_run)
svm_clear_vintr(svm);
svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
+ /* Let's try to emulate as many instructions as possible in GIF=0 */
+
+ while(true) {
+ int er;
+
+ er = emulate_instruction(&svm->vcpu, kvm_run, 0, 0, 0);
+ nsvm_printk("NSVM: emulating at 0x%lx -> %d\n",
svm->vcpu.arch.regs[VCPU_REGS_RIP], er);
+
+ /* So we can now emulate the SVM instructions that most probably
+ occur at the end of the codepath */
+ if (er != EMULATE_DONE) {
+ while (true)
+ if (nested_svm_emulate(svm, kvm_run) ==
EMULATE_FAIL)
+ break;
+ break;
+ }
+ }
return 1;
}
--
1.5.6
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