diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0081-KVM-x86-Update-cpuid-properly-when-CR4.OSXAVE-or-CR4.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0081-KVM-x86-Update-cpuid-properly-when-CR4.OSXAVE-or-CR4.patch | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0081-KVM-x86-Update-cpuid-properly-when-CR4.OSXAVE-or-CR4.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0081-KVM-x86-Update-cpuid-properly-when-CR4.OSXAVE-or-CR4.patch new file mode 100644 index 00000000..f44b77a1 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0081-KVM-x86-Update-cpuid-properly-when-CR4.OSXAVE-or-CR4.patch @@ -0,0 +1,63 @@ +From a41340930388022d17c5acfa7c00edc80fa486f6 Mon Sep 17 00:00:00 2001 +From: Wei Huang <wei@redhat.com> +Date: Tue, 1 May 2018 09:49:54 -0500 +Subject: [PATCH 81/93] KVM: x86: Update cpuid properly when CR4.OSXAVE or + CR4.PKE is changed +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +commit c4d2188206bafa177ea58e9a25b952baa0bf7712 upstream. + +The CPUID bits of OSXSAVE (function=0x1) and OSPKE (func=0x7, leaf=0x0) +allows user apps to detect if OS has set CR4.OSXSAVE or CR4.PKE. KVM is +supposed to update these CPUID bits when CR4 is updated. Current KVM +code doesn't handle some special cases when updates come from emulator. +Here is one example: + + Step 1: guest boots + Step 2: guest OS enables XSAVE ==> CR4.OSXSAVE=1 and CPUID.OSXSAVE=1 + Step 3: guest hot reboot ==> QEMU reset CR4 to 0, but CPUID.OSXAVE==1 + Step 4: guest os checks CPUID.OSXAVE, detects 1, then executes xgetbv + +Step 4 above will cause an #UD and guest crash because guest OS hasn't +turned on OSXAVE yet. This patch solves the problem by comparing the the +old_cr4 with cr4. If the related bits have been changed, +kvm_update_cpuid() needs to be called. + +Signed-off-by: Wei Huang <wei@redhat.com> +Reviewed-by: Bandan Das <bsd@redhat.com> +Cc: stable@vger.kernel.org +Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/kvm/x86.c | 5 ++++- + 1 file changed, 4 insertions(+), 1 deletion(-) + +diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c +index c531231..27e6cf0 100644 +--- a/arch/x86/kvm/x86.c ++++ b/arch/x86/kvm/x86.c +@@ -7201,6 +7201,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, + { + struct msr_data apic_base_msr; + int mmu_reset_needed = 0; ++ int cpuid_update_needed = 0; + int pending_vec, max_bits, idx; + struct desc_ptr dt; + +@@ -7232,8 +7233,10 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, + vcpu->arch.cr0 = sregs->cr0; + + mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4; ++ cpuid_update_needed |= ((kvm_read_cr4(vcpu) ^ sregs->cr4) & ++ (X86_CR4_OSXSAVE | X86_CR4_PKE)); + kvm_x86_ops->set_cr4(vcpu, sregs->cr4); +- if (sregs->cr4 & (X86_CR4_OSXSAVE | X86_CR4_PKE)) ++ if (cpuid_update_needed) + kvm_update_cpuid(vcpu); + + idx = srcu_read_lock(&vcpu->kvm->srcu); +-- +2.7.4 + |