From 1fbdc7a58512a6283e10fd27108197679db95ffa Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Sun, 11 Jan 2009 22:39:44 +0100 Subject: [PATCH] KVM: SVM: set accessed bit for VMCB segment selectors In the segment descriptor _cache_ the accessed bit is always set (although it can be cleared in the descriptor itself). Since Intel checks for this condition on a VMENTRY, set this bit in the AMD path to enable cross vendor migration. Cc: stable@kernel.org Signed-off-by: Andre Przywara Acked-By: Amit Shah Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 22e88a4a51c..1821c207819 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -796,20 +796,37 @@ static void svm_get_segment(struct kvm_vcpu *vcpu, var->db = (s->attrib >> SVM_SELECTOR_DB_SHIFT) & 1; var->g = (s->attrib >> SVM_SELECTOR_G_SHIFT) & 1; - /* - * SVM always stores 0 for the 'G' bit in the CS selector in - * the VMCB on a VMEXIT. This hurts cross-vendor migration: - * Intel's VMENTRY has a check on the 'G' bit. - */ - if (seg == VCPU_SREG_CS) + switch (seg) { + case VCPU_SREG_CS: + /* + * SVM always stores 0 for the 'G' bit in the CS selector in + * the VMCB on a VMEXIT. This hurts cross-vendor migration: + * Intel's VMENTRY has a check on the 'G' bit. + */ var->g = s->limit > 0xfffff; - - /* - * Work around a bug where the busy flag in the tr selector - * isn't exposed - */ - if (seg == VCPU_SREG_TR) + break; + case VCPU_SREG_TR: + /* + * Work around a bug where the busy flag in the tr selector + * isn't exposed + */ var->type |= 0x2; + break; + case VCPU_SREG_DS: + case VCPU_SREG_ES: + case VCPU_SREG_FS: + case VCPU_SREG_GS: + /* + * The accessed bit must always be set in the segment + * descriptor cache, although it can be cleared in the + * descriptor, the cached bit always remains at 1. Since + * Intel has a check on this, set it here to support + * cross-vendor migration. + */ + if (!var->unusable) + var->type |= 0x1; + break; + } var->unusable = !var->present; } -- 2.41.1