On Tue, Apr 11, 2023 at 03:49:38PM +0300,
Zhi Wang <zhi.wang.linux@xxxxxxxxx> wrote:
> On Sun, 12 Mar 2023 10:56:28 -0700
> isaku.yamahata@xxxxxxxxx wrote:
>
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> >
> > This patch implements running TDX vcpu. Once vcpu runs on the logical
> > processor (LP), the TDX vcpu is associated with it. When the TDX vcpu
> > moves to another LP, the TDX vcpu needs to flush its status on the LP.
> > When destroying TDX vcpu, it needs to complete flush and flush cpu memory
> > cache. Track which LP the TDX vcpu run and flush it as necessary.
> >
> > Do nothing on sched_in event as TDX doesn't support pause loop.
> >
> > TDX vcpu execution requires restoring PMU debug store after returning back
> > to KVM because the TDX module unconditionally resets the value. To reuse
> > the existing code, export perf_restore_debug_store.
> >
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > ---
> > arch/x86/kvm/vmx/main.c | 21 +++++++++++++++++++--
> > arch/x86/kvm/vmx/tdx.c | 32 ++++++++++++++++++++++++++++++++
> > arch/x86/kvm/vmx/tdx.h | 33 +++++++++++++++++++++++++++++++++
> > arch/x86/kvm/vmx/x86_ops.h | 2 ++
> > arch/x86/kvm/x86.c | 1 +
> > 5 files changed, 87 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> > index 55001b34e1f0..2fd6c954590d 100644
> > --- a/arch/x86/kvm/vmx/main.c
> > +++ b/arch/x86/kvm/vmx/main.c
> > @@ -170,6 +170,23 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> > vmx_vcpu_reset(vcpu, init_event);
> > }
> >
> > +static int vt_vcpu_pre_run(struct kvm_vcpu *vcpu)
> > +{
> > + if (is_td_vcpu(vcpu))
> > + /* Unconditionally continue to vcpu_run(). */
> > + return 1;
> > +
> > + return vmx_vcpu_pre_run(vcpu);
> > +}
> > +
> > +static fastpath_t vt_vcpu_run(struct kvm_vcpu *vcpu)
> > +{
> > + if (is_td_vcpu(vcpu))
> > + return tdx_vcpu_run(vcpu);
> > +
> > + return vmx_vcpu_run(vcpu);
> > +}
> > +
> > static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
> > {
> > if (is_td_vcpu(vcpu)) {
> > @@ -323,8 +340,8 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> > .flush_tlb_gva = vt_flush_tlb_gva,
> > .flush_tlb_guest = vt_flush_tlb_guest,
> >
> > - .vcpu_pre_run = vmx_vcpu_pre_run,
> > - .vcpu_run = vmx_vcpu_run,
> > + .vcpu_pre_run = vt_vcpu_pre_run,
> > + .vcpu_run = vt_vcpu_run,
> > .handle_exit = vmx_handle_exit,
> > .skip_emulated_instruction = vmx_skip_emulated_instruction,
> > .update_emulated_instruction = vmx_update_emulated_instruction,
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index d5a2f769a58d..28a19b14cbbc 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -11,6 +11,9 @@
> > #include "x86.h"
> > #include "mmu.h"
> >
> > +#include <trace/events/kvm.h>
> > +#include "trace.h"
> > +
> > #undef pr_fmt
> > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> >
> > @@ -439,6 +442,35 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> > */
> > }
> >
> > +u64 __tdx_vcpu_run(hpa_t tdvpr, void *regs, u32 regs_mask);
> > +
> > +static noinstr void tdx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
> > + struct vcpu_tdx *tdx)
> > +{
> > + guest_enter_irqoff();
> > + tdx->exit_reason.full = __tdx_vcpu_run(tdx->tdvpr_pa, vcpu->arch.regs, 0);
> > + guest_exit_irqoff();
> > +}
> > +
> > +fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)
> > +{
> > + struct vcpu_tdx *tdx = to_tdx(vcpu);
> > +
> > + if (unlikely(vcpu->kvm->vm_bugged)) {
> > + tdx->exit_reason.full = TDX_NON_RECOVERABLE_VCPU;
> > + return EXIT_FASTPATH_NONE;
> > + }
> > +
>
> Maybe check if a TD vCPU is initialized here or in the vcpu_pre_run?
I don't see any point to add tdx_pre_run() and to move the check there.
> Bascially
> I am thinking what if a TD vCPU is not initialized by KVM_TDX_INIT_VCPU (TDVPR
> does not even exist) and now userspace wants to run it. What would be the
> consequence?
TDENTER will fail with error code. Let's add explicit check here for safetly.
if (unlikly(!tdx->initialized))
return -EINVAL;
--
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
