diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0082-kvm-x86-IA32_ARCH_CAPABILITIES-is-always-supported.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0082-kvm-x86-IA32_ARCH_CAPABILITIES-is-always-supported.patch | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0082-kvm-x86-IA32_ARCH_CAPABILITIES-is-always-supported.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0082-kvm-x86-IA32_ARCH_CAPABILITIES-is-always-supported.patch new file mode 100644 index 00000000..313f2577 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0082-kvm-x86-IA32_ARCH_CAPABILITIES-is-always-supported.patch @@ -0,0 +1,54 @@ +From e34ebcda27df86037fd748254208aff7e442ff0b Mon Sep 17 00:00:00 2001 +From: Jim Mattson <jmattson@google.com> +Date: Wed, 9 May 2018 14:29:35 -0700 +Subject: [PATCH 82/93] kvm: x86: IA32_ARCH_CAPABILITIES is always supported +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +commit 1eaafe91a0df4157521b6417b3dd8430bf5f52f0 upstream. + +If there is a possibility that a VM may migrate to a Skylake host, +then the hypervisor should report IA32_ARCH_CAPABILITIES.RSBA[bit 2] +as being set (future work, of course). This implies that +CPUID.(EAX=7,ECX=0):EDX.ARCH_CAPABILITIES[bit 29] should be +set. Therefore, kvm should report this CPUID bit as being supported +whether or not the host supports it. Userspace is still free to clear +the bit if it chooses. + +For more information on RSBA, see Intel's white paper, "Retpoline: A +Branch Target Injection Mitigation" (Document Number 337131-001), +currently available at https://bugzilla.kernel.org/show_bug.cgi?id=199511. + +Since the IA32_ARCH_CAPABILITIES MSR is emulated in kvm, there is no +dependency on hardware support for this feature. + +Signed-off-by: Jim Mattson <jmattson@google.com> +Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> +Fixes: 28c1c9fabf48 ("KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES") +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/cpuid.c | 5 +++++ + 1 file changed, 5 insertions(+) + +diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c +index 8510b7b..fbd6c62 100644 +--- a/arch/x86/kvm/cpuid.c ++++ b/arch/x86/kvm/cpuid.c +@@ -468,6 +468,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, + entry->ecx &= ~F(PKU); + entry->edx &= kvm_cpuid_7_0_edx_x86_features; + cpuid_mask(&entry->edx, CPUID_7_EDX); ++ /* ++ * We emulate ARCH_CAPABILITIES in software even ++ * if the host doesn't support it. ++ */ ++ entry->edx |= F(ARCH_CAPABILITIES); + } else { + entry->ebx = 0; + entry->ecx = 0; +-- +2.7.4 + |