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    SubjectRe: [PATCH] KVM: VMX: fix tlb flush with invalid root
    Date
    On Saturday 03 July 2010 16:02:42 Xiao Guangrong wrote:
    > Commit 341d9b535b6c simplify reload logic while entry guest mode, it
    > can avoid unnecessary sync-root if KVM_REQ_MMU_RELOAD and
    > KVM_REQ_MMU_SYNC both set.

    Which commit you are talking about? Can't find 341d9b535b6c...

    --
    regards
    Yang, Sheng

    >
    > But, it cause a issue that when we handle 'KVM_REQ_TLB_FLUSH', the
    > root is invalid, it is triggered during my test:
    >
    > Kernel BUG at ffffffffa00212b8 [verbose debug info unavailable]
    > ......
    >
    > [<ffffffff810f5caf>] ? fget_light+0x111/0x28e
    > [<ffffffff81103963>] sys_ioctl+0x47/0x6a
    > [<ffffffff81002c1b>] system_call_fastpath+0x16/0x1b
    > Code: f0 eb 21 f7 c2 00 00 00 04 74 22 48 8d 45 f0 48 c7 45 f0 00 00 00 00
    > 48 c7 45 f8 00 00 00 00 b9 02 00 00 00 66 0f 38 80 08 77 02 <0f> 0b c9 c3
    > 55 48 89 e5 0f 1f 44 00 00 ba 00 68 00 00 48 8b 8f RIP
    > [<ffffffffa00212b8>] vmx_flush_tlb+0xdf/0xe3 [kvm_intel]
    > RSP <ffff8800be269ca8>
    >
    > Fixed by directly return if the root is not ready.
    >
    > Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
    > ---
    > arch/x86/include/asm/kvm_host.h | 2 ++
    > arch/x86/kvm/mmu.c | 2 --
    > arch/x86/kvm/vmx.c | 5 ++++-
    > 3 files changed, 6 insertions(+), 3 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/kvm_host.h
    > b/arch/x86/include/asm/kvm_host.h index 2bda624..8f522ec 100644
    > --- a/arch/x86/include/asm/kvm_host.h
    > +++ b/arch/x86/include/asm/kvm_host.h
    > @@ -40,6 +40,8 @@
    > 0xFFFFFF0000000000ULL)
    >
    > #define INVALID_PAGE (~(hpa_t)0)
    > +#define VALID_PAGE(x) ((x) != INVALID_PAGE)
    > +
    > #define UNMAPPED_GVA (~(gpa_t)0)
    >
    > /* KVM Hugepage definitions for x86 */
    > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    > index a0c5c31..399ddb0 100644
    > --- a/arch/x86/kvm/mmu.c
    > +++ b/arch/x86/kvm/mmu.c
    > @@ -92,8 +92,6 @@ module_param(oos_shadow, bool, 0644);
    > #define PT_FIRST_AVAIL_BITS_SHIFT 9
    > #define PT64_SECOND_AVAIL_BITS_SHIFT 52
    >
    > -#define VALID_PAGE(x) ((x) != INVALID_PAGE)
    > -
    > #define PT64_LEVEL_BITS 9
    >
    > #define PT64_LEVEL_SHIFT(level) \
    > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    > index 806ab12..ebaaeaf 100644
    > --- a/arch/x86/kvm/vmx.c
    > +++ b/arch/x86/kvm/vmx.c
    > @@ -1831,8 +1831,11 @@ static void exit_lmode(struct kvm_vcpu *vcpu)
    > static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
    > {
    > vpid_sync_context(to_vmx(vcpu));
    > - if (enable_ept)
    > + if (enable_ept) {
    > + if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
    > + return;
    > ept_sync_context(construct_eptp(vcpu->arch.mmu.root_hpa));
    > + }
    > }
    >
    > static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)


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