From: Jim Mattson <jmattson@google.com>
To: Yu Zhang <yu.c.zhang@linux.intel.com>
Cc: "kvm list" <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
xiaoguangrong@tencent.com, "Joerg Roedel" <joro@8bytes.org>
Subject: Re: [PATCH v1 1/4] KVM: MMU: check guest CR3 reserved bits based on its physical address width.
Date: Mon, 14 Aug 2017 09:13:11 -0700 [thread overview]
Message-ID: <CALMp9eS1r30miVs-p4p5WLm1vn=FAGMkLxbjRWcLzw97ctp_XA@mail.gmail.com> (raw)
In-Reply-To: <1502544906-1108-2-git-send-email-yu.c.zhang@linux.intel.com>
On Sat, Aug 12, 2017 at 6:35 AM, Yu Zhang <yu.c.zhang@linux.intel.com> wrote:
> Currently, KVM uses CR3_L_MODE_RESERVED_BITS to check the
> reserved bits in CR3. Yet the length of reserved bits in
> guest CR3 should be based on the physical address width
> exposed to the VM. This patch changes CR3 check logic to
> calculate the reserved bits at runtime.
>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 1 -
> arch/x86/kvm/emulate.c | 12 ++++++++++--
> arch/x86/kvm/x86.c | 8 ++++----
> 3 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 9e4862e..018300e 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -79,7 +79,6 @@
> | X86_CR0_ET | X86_CR0_NE | X86_CR0_WP | X86_CR0_AM \
> | X86_CR0_NW | X86_CR0_CD | X86_CR0_PG))
>
> -#define CR3_L_MODE_RESERVED_BITS 0xFFFFFF0000000000ULL
> #define CR3_PCID_INVD BIT_64(63)
> #define CR4_RESERVED_BITS \
> (~(unsigned long)(X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE\
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index fb00559..a98b88a 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -4097,8 +4097,16 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt)
> u64 rsvd = 0;
>
> ctxt->ops->get_msr(ctxt, MSR_EFER, &efer);
> - if (efer & EFER_LMA)
> - rsvd = CR3_L_MODE_RESERVED_BITS & ~CR3_PCID_INVD;
> + if (efer & EFER_LMA) {
> + u64 maxphyaddr;
> + u32 eax = 0x80000008;
> +
> + ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL, NULL);
> + maxphyaddr = eax * 0xff;
What if leaf 0x80000008 is not defined?
> +
> + rsvd = (~((1UL << maxphyaddr) - 1)) &
> + ~CR3_PCID_INVD;
> + }
>
> if (new_val & rsvd)
> return emulate_gp(ctxt, 0);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e40a779..d9100c4 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -813,10 +813,10 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
> return 0;
> }
>
> - if (is_long_mode(vcpu)) {
> - if (cr3 & CR3_L_MODE_RESERVED_BITS)
> - return 1;
> - } else if (is_pae(vcpu) && is_paging(vcpu) &&
> + if (is_long_mode(vcpu) &&
> + (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))
> + return 1;
> + else if (is_pae(vcpu) && is_paging(vcpu) &&
> !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
> return 1;
>
> --
> 2.5.0
>
next prev parent reply other threads:[~2017-08-14 16:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-12 13:35 [PATCH v1 0/4] KVM: MMU: 5 level EPT/shadow support Yu Zhang
2017-08-12 13:35 ` [PATCH v1 1/4] KVM: MMU: check guest CR3 reserved bits based on its physical address width Yu Zhang
2017-08-14 7:36 ` Paolo Bonzini
2017-08-14 11:39 ` Yu Zhang
2017-08-14 16:13 ` Jim Mattson [this message]
2017-08-14 16:40 ` Paolo Bonzini
2017-08-15 7:50 ` Yu Zhang
2017-08-12 13:35 ` [PATCH v1 2/4] KVM: MMU: Rename PT64_ROOT_LEVEL to PT64_ROOT_4LEVEL Yu Zhang
2017-08-12 13:35 ` [PATCH v1 3/4] KVM: MMU: Add 5 level EPT & Shadow page table support Yu Zhang
2017-08-14 7:31 ` Paolo Bonzini
2017-08-14 11:37 ` Yu Zhang
2017-08-14 14:13 ` Paolo Bonzini
2017-08-14 14:32 ` Yu Zhang
2017-08-14 15:02 ` Paolo Bonzini
2017-08-14 14:55 ` Yu Zhang
2017-08-12 13:35 ` [PATCH v1 4/4] KVM: MMU: Expose the LA57 feature to VM Yu Zhang
2017-08-17 11:57 ` Paolo Bonzini
2017-08-17 11:53 ` Yu Zhang
2017-08-17 14:29 ` Paolo Bonzini
2017-08-18 8:28 ` Yu Zhang
2017-08-18 12:50 ` Paolo Bonzini
2017-08-21 7:27 ` Yu Zhang
2017-08-21 10:12 ` Paolo Bonzini
2017-08-21 12:11 ` Yu Zhang
2017-08-14 7:32 ` [PATCH v1 0/4] KVM: MMU: 5 level EPT/shadow support Paolo Bonzini
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