[PATCH RT 05/12 rc3] KVM: fix XSAVE bit scanning (now properly)
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2011-12-05 23:03:10
Also in:
lkml
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Andre Przywara <redacted> commit 123108f1c1aafd51d6a5c79cc04d7999dd88a930 tried to fix KVMs XSAVE valid feature scanning, but it was wrong. It was not considering the sparse nature of this bitfield, instead reading values from uninitialized members of the entries array. This patch now separates subleaf indicies from KVM's array indicies and fills the entry before querying it's value. This fixes AVX support in KVM guests. Signed-off-by: Andre Przywara <redacted> Signed-off-by: Avi Kivity <redacted> --- arch/x86/kvm/x86.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f168c61..3567c76 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -2419,16 +2419,17 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, break; } case 0xd: { - int i; + int idx, i; entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; - for (i = 1; *nent < maxnent && i < 64; ++i) { - if (entry[i].eax == 0 || !supported_xcr0_bit(i)) + for (idx = 1, i = 1; *nent < maxnent && idx < 64; ++idx) { + do_cpuid_1_ent(&entry[i], function, idx); + if (entry[i].eax == 0 || !supported_xcr0_bit(idx)) continue; - do_cpuid_1_ent(&entry[i], function, i); entry[i].flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; ++*nent; + ++i; } break; }
--
1.7.7.1
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