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From 780079c8c61ea452198d8cd3f0363543ee84d7fc Mon Sep 17 00:00:00 2001 |
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From: Jim Mattson <jmattson@google.com> |
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Date: Fri, 21 Sep 2018 10:36:17 -0700 |
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Subject: [PATCH 094/145] KVM: nVMX: Clear reserved bits of #DB exit |
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qualification |
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|
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[ Upstream commit cfb634fe3052aefc4e1360fa322018c9a0b49755 ] |
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|
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According to volume 3 of the SDM, bits 63:15 and 12:4 of the exit |
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qualification field for debug exceptions are reserved (cleared to |
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0). However, the SDM is incorrect about bit 16 (corresponding to |
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DR6.RTM). This bit should be set if a debug exception (#DB) or a |
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breakpoint exception (#BP) occurred inside an RTM region while |
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advanced debugging of RTM transactional regions was enabled. Note that |
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this is the opposite of DR6.RTM, which "indicates (when clear) that a |
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debug exception (#DB) or breakpoint exception (#BP) occurred inside an |
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RTM region while advanced debugging of RTM transactional regions was |
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enabled." |
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|
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There is still an issue with stale DR6 bits potentially being |
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misreported for the current debug exception. DR6 should not have been |
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modified before vectoring the #DB exception, and the "new DR6 bits" |
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should be available somewhere, but it was and they aren't. |
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|
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Fixes: b96fb439774e1 ("KVM: nVMX: fixes to nested virt interrupt injection") |
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Signed-off-by: Jim Mattson <jmattson@google.com> |
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Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com> |
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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Signed-off-by: Sasha Levin <sashal@kernel.org> |
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--- |
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arch/x86/include/asm/kvm_host.h | 1 + |
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arch/x86/kvm/vmx.c | 7 +++++-- |
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2 files changed, 6 insertions(+), 2 deletions(-) |
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|
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diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h |
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index 09b2e3e2cf1b..1c09a0d1771f 100644 |
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--- a/arch/x86/include/asm/kvm_host.h |
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+++ b/arch/x86/include/asm/kvm_host.h |
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@@ -177,6 +177,7 @@ enum { |
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|
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#define DR6_BD (1 << 13) |
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#define DR6_BS (1 << 14) |
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+#define DR6_BT (1 << 15) |
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#define DR6_RTM (1 << 16) |
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#define DR6_FIXED_1 0xfffe0ff0 |
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#define DR6_INIT 0xffff0ff0 |
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diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c |
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index e665aa7167cf..a933ce5ec1ff 100644 |
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--- a/arch/x86/kvm/vmx.c |
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+++ b/arch/x86/kvm/vmx.c |
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@@ -3294,10 +3294,13 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned long *exit |
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} |
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} else { |
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if (vmcs12->exception_bitmap & (1u << nr)) { |
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- if (nr == DB_VECTOR) |
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+ if (nr == DB_VECTOR) { |
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*exit_qual = vcpu->arch.dr6; |
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- else |
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+ *exit_qual &= ~(DR6_FIXED_1 | DR6_BT); |
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+ *exit_qual ^= DR6_RTM; |
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+ } else { |
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*exit_qual = 0; |
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+ } |
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return 1; |
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} |
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} |
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-- |
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2.19.1 |
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