RE: [PATCH v3 02/11] KVM: SVM: Change intercept_cr to generic intercepts

Babu Moger
2020-07-29T16:08:35Z

> -----Original Message-----
> From: Jim Mattson <jmattson@google.com>
> Sent: Tuesday, July 28, 2020 6:56 PM
> To: Moger, Babu <Babu.Moger@amd.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>; Vitaly Kuznetsov
> <vkuznets@redhat.com>; Wanpeng Li <wanpengli@tencent.com>; Sean
> Christopherson <sean.j.christopherson@intel.com>; kvm list
> <kvm@vger.kernel.org>; Joerg Roedel <joro@8bytes.org>; the arch/x86
> maintainers <x86@kernel.org>; LKML <linux-kernel@vger.kernel.org>; Ingo
> Molnar <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>; H . Peter Anvin
> <hpa@zytor.com>; Thomas Gleixner <tglx@linutronix.de>
> Subject: Re: [PATCH v3 02/11] KVM: SVM: Change intercept_cr to generic
> intercepts
>
> On Tue, Jul 28, 2020 at 4:38 PM Babu Moger <babu.moger@amd.com> wrote:
> >
> > Change intercept_cr to generic intercepts in vmcb_control_area.
> > Use the new __set_intercept, __clr_intercept and __is_intercept where
> > applicable.
> >
> > Signed-off-by: Babu Moger <babu.moger@amd.com>
> > ---
> > arch/x86/include/asm/svm.h | 42 ++++++++++++++++++++++++++++++++----
> ------
> > arch/x86/kvm/svm/nested.c | 26 +++++++++++++++++---------
> > arch/x86/kvm/svm/svm.c | 4 ++--
> > arch/x86/kvm/svm/svm.h | 6 +++---
> > 4 files changed, 54 insertions(+), 24 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> > index 8a1f5382a4ea..d4739f4eae63 100644
> > --- a/arch/x86/include/asm/svm.h
> > +++ b/arch/x86/include/asm/svm.h
> > @@ -4,6 +4,37 @@
> >
> > #include <uapi/asm/svm.h>
> >
> > +/*
> > + * VMCB Control Area intercept bits starting
> > + * at Byte offset 000h (Vector 0).
> > + */
> > +
> > +enum vector_offset {
> > + CR_VECTOR = 0,
> > + MAX_VECTORS,
> > +};
> > +
> > +enum {
> > + /* Byte offset 000h (Vector 0) */
> > + INTERCEPT_CR0_READ = 0,
> > + INTERCEPT_CR1_READ,
> > + INTERCEPT_CR2_READ,
> > + INTERCEPT_CR3_READ,
> > + INTERCEPT_CR4_READ,
> > + INTERCEPT_CR5_READ,
> > + INTERCEPT_CR6_READ,
> > + INTERCEPT_CR7_READ,
> > + INTERCEPT_CR8_READ,
> > + INTERCEPT_CR0_WRITE = 16,
> > + INTERCEPT_CR1_WRITE,
> > + INTERCEPT_CR2_WRITE,
> > + INTERCEPT_CR3_WRITE,
> > + INTERCEPT_CR4_WRITE,
> > + INTERCEPT_CR5_WRITE,
> > + INTERCEPT_CR6_WRITE,
> > + INTERCEPT_CR7_WRITE,
> > + INTERCEPT_CR8_WRITE,
> > +};
> >
> > enum {
> > INTERCEPT_INTR,
> > @@ -57,7 +88,7 @@ enum {
> >
> >
> > struct __attribute__ ((__packed__)) vmcb_control_area {
> > - u32 intercept_cr;
> > + u32 intercepts[MAX_VECTORS];
> > u32 intercept_dr;
> > u32 intercept_exceptions;
> > u64 intercept;
> > @@ -240,15 +271,6 @@ struct __attribute__ ((__packed__)) vmcb {
> > #define SVM_SELECTOR_READ_MASK SVM_SELECTOR_WRITE_MASK #define
> > SVM_SELECTOR_CODE_MASK (1 << 3)
> >
> > -#define INTERCEPT_CR0_READ 0
> > -#define INTERCEPT_CR3_READ 3
> > -#define INTERCEPT_CR4_READ 4
> > -#define INTERCEPT_CR8_READ 8
> > -#define INTERCEPT_CR0_WRITE (16 + 0)
> > -#define INTERCEPT_CR3_WRITE (16 + 3)
> > -#define INTERCEPT_CR4_WRITE (16 + 4)
> > -#define INTERCEPT_CR8_WRITE (16 + 8)
> > -
> > #define INTERCEPT_DR0_READ 0
> > #define INTERCEPT_DR1_READ 1
> > #define INTERCEPT_DR2_READ 2
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index 6bceafb19108..46f5c82d9b45 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -105,6 +105,7 @@ static void nested_svm_uninit_mmu_context(struct
> > kvm_vcpu *vcpu) void recalc_intercepts(struct vcpu_svm *svm) {
> > struct vmcb_control_area *c, *h, *g;
> > + unsigned int i;
> >
> > mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
> >
> > @@ -117,15 +118,17 @@ void recalc_intercepts(struct vcpu_svm *svm)
> >
> > svm->nested.host_intercept_exceptions =
> > h->intercept_exceptions;
> >
> > - c->intercept_cr = h->intercept_cr;
> > + for (i = 0; i < MAX_VECTORS; i++)
> > + c->intercepts[i] = h->intercepts[i];
> > +
> > c->intercept_dr = h->intercept_dr;
> > c->intercept_exceptions = h->intercept_exceptions;
> > c->intercept = h->intercept;
> >
> > if (g->int_ctl & V_INTR_MASKING_MASK) {
> > /* We only want the cr8 intercept bits of L1 */
> > - c->intercept_cr &= ~(1U << INTERCEPT_CR8_READ);
> > - c->intercept_cr &= ~(1U << INTERCEPT_CR8_WRITE);
> > + __clr_intercept(&c->intercepts, INTERCEPT_CR8_READ);
> > + __clr_intercept(&c->intercepts, INTERCEPT_CR8_WRITE);
>
> Why the direct calls to the __clr_intercept worker function? Can't these be calls
> to clr_cr_intercept()?
> Likewise throughout.

This code uses the address to clear the bits. So called __clr_intercept
directly. The call clr_cr_intercept() passes the structure vcpu_svm and
then uses get_host_vmcb to get the address.