From 777ab82d7ce0451fd47bb57e331548deba57394e Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 7 Dec 2021 17:52:30 +0800 Subject: KVM: X86: Raise #GP when clearing CR0_PG in 64 bit mode In the SDM: If the logical processor is in 64-bit mode or if CR4.PCIDE = 1, an attempt to clear CR0.PG causes a general-protection exception (#GP). Software should transition to compatibility mode and clear CR4.PCIDE before attempting to disable paging. Signed-off-by: Lai Jiangshan Message-Id: <20211207095230.53437-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e0aa4dd53c7f..c473498c8512 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -890,7 +890,8 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) !load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu))) return 1; - if (!(cr0 & X86_CR0_PG) && kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE)) + if (!(cr0 & X86_CR0_PG) && + (is_64_bit_mode(vcpu) || kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE))) return 1; static_call(kvm_x86_set_cr0)(vcpu, cr0); -- cgit v1.2.3 From d07898eaf39909806128caccb6ebd922ee3edd69 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 25 Oct 2021 13:13:10 -0700 Subject: KVM: x86: Don't WARN if userspace mucks with RCX during string I/O exit Replace a WARN with a comment to call out that userspace can modify RCX during an exit to userspace to handle string I/O. KVM doesn't actually support changing the rep count during an exit, i.e. the scenario can be ignored, but the WARN needs to go as it's trivial to trigger from userspace. Cc: stable@vger.kernel.org Fixes: 3b27de271839 ("KVM: x86: split the two parts of emulator_pio_in") Signed-off-by: Sean Christopherson Message-Id: <20211025201311.1881846-2-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c473498c8512..0cf1082455df 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7122,7 +7122,13 @@ static int emulator_pio_in(struct kvm_vcpu *vcpu, int size, unsigned short port, void *val, unsigned int count) { if (vcpu->arch.pio.count) { - /* Complete previous iteration. */ + /* + * Complete a previous iteration that required userspace I/O. + * Note, @count isn't guaranteed to match pio.count as userspace + * can modify ECX before rerunning the vCPU. Ignore any such + * shenanigans as KVM doesn't support modifying the rep count, + * and the emulator ensures @count doesn't overflow the buffer. + */ } else { int r = __emulator_pio_in(vcpu, size, port, count); if (!r) @@ -7131,7 +7137,6 @@ static int emulator_pio_in(struct kvm_vcpu *vcpu, int size, /* Results already available, fall through. */ } - WARN_ON(count != vcpu->arch.pio.count); complete_emulator_pio_in(vcpu, val); return 1; } -- cgit v1.2.3 From 1aa2abb33a419090c7c87d4ae842a6347078ee12 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 16 Dec 2021 17:52:13 +0100 Subject: KVM: x86: Drop guest CPUID check for host initiated writes to MSR_IA32_PERF_CAPABILITIES The ability to write to MSR_IA32_PERF_CAPABILITIES from the host should not depend on guest visible CPUID entries, even if just to allow creating/restoring guest MSRs and CPUIDs in any sequence. Fixes: 27461da31089 ("KVM: x86/pmu: Support full width counting") Suggested-by: Sean Christopherson Signed-off-by: Vitaly Kuznetsov Message-Id: <20211216165213.338923-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0cf1082455df..9a2972fdae82 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3413,7 +3413,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (!msr_info->host_initiated) return 1; - if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM) && kvm_get_msr_feature(&msr_ent)) + if (kvm_get_msr_feature(&msr_ent)) return 1; if (data & ~msr_ent.data) return 1; -- cgit v1.2.3