KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time

BugLink: https://bugs.launchpad.net/bugs/1959879
commit 05a9e065059e566f218f8778c4d17ee75db56c55 upstream.

XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
also needs to update kvm_update_cpuid_runtime(). In the above cases, the
size in bytes of the XSAVE area containing all states enabled by XCR0 or
(XCRO | IA32_XSS) needs to be updated.

For simplicity and consistency, existing helpers are used to write values
and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.

Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
Cc: stable@vger.kernel.org
Signed-off-by: Like Xu <likexu@tencent.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220126172226.2298529-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd57011f6d14cbb7fd6a01434d38d74ce57c6ddc..5b497824f8d53eb7eb72f3f9d534d78ebeff882e 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10990,8 +10990,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
                vcpu->arch.msr_misc_features_enables = 0;
 
-               vcpu->arch.xcr0 = XFEATURE_MASK_FP;
-               vcpu->arch.ia32_xss = 0;
+               __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
+               __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
        }
 
        memset(vcpu->arch.regs, 0, sizeof(vcpu->arch.regs));