kernel/linux.git/arch, branch v4.19.103

x86/apic/msi: Plug non-maskable MSI affinity race

2020-02-11T12:34:18+00:00

commit 6f1a4891a5928a5969c87fa5a584844c983ec823 upstream. Evan tracked down a subtle race between the update of the MSI message and the device raising an interrupt internally on PCI devices which do not support MSI masking. The update of the MSI message is non-atomic and consists of either 2 or 3 sequential 32bit wide writes to the PCI config space. - Write address low 32bits - Write address high 32bits (If supported by device) - Write data When an interrupt is migrated then both address and data might change, so the kernel attempts to mask the MSI interrupt first. But for MSI masking is optional, so there exist devices which do not provide it. That means that if the device raises an interrupt internally between the writes then a MSI message is sent built from half updated state. On x86 this can lead to spurious interrupts on the wrong interrupt vector when the affinity setting changes both address and data. As a consequence the device interrupt can be lost causing the device to become stuck or malfunctioning. Evan tried to handle that by disabling MSI accross an MSI message update. That's not feasible because disabling MSI has issues on its own: If MSI is disabled the PCI device is routing an interrupt to the legacy INTx mechanism. The INTx delivery can be disabled, but the disablement is not working on all devices. Some devices lose interrupts when both MSI and INTx delivery are disabled. Another way to solve this would be to enforce the allocation of the same vector on all CPUs in the system for this kind of screwed devices. That could be done, but it would bring back the vector space exhaustion problems which got solved a few years ago. Fortunately the high address (if supported by the device) is only relevant when X2APIC is enabled which implies interrupt remapping. In the interrupt remapping case the affinity setting is happening at the interrupt remapping unit and the PCI MSI message is programmed only once when the PCI device is initialized. That makes it possible to solve it with a two step update: 1) Target the MSI msg to the new vector on the current target CPU 2) Target the MSI msg to the new vector on the new target CPU In both cases writing the MSI message is only changing a single 32bit word which prevents the issue of inconsistency. After writing the final destination it is necessary to check whether the device issued an interrupt while the intermediate state #1 (new vector, current CPU) was in effect. This is possible because the affinity change is always happening on the current target CPU. The code runs with interrupts disabled, so the interrupt can be detected by checking the IRR of the local APIC. If the vector is pending in the IRR then the interrupt is retriggered on the new target CPU by sending an IPI for the associated vector on the target CPU. This can cause spurious interrupts on both the local and the new target CPU. 1) If the new vector is not in use on the local CPU and the device affected by the affinity change raised an interrupt during the transitional state (step #1 above) then interrupt entry code will ignore that spurious interrupt. The vector is marked so that the 'No irq handler for vector' warning is supressed once. 2) If the new vector is in use already on the local CPU then the IRR check might see an pending interrupt from the device which is using this vector. The IPI to the new target CPU will then invoke the handler of the device, which got the affinity change, even if that device did not issue an interrupt 3) If the new vector is in use already on the local CPU and the device affected by the affinity change raised an interrupt during the transitional state (step #1 above) then the handler of the device which uses that vector on the local CPU will be invoked. expose issues in device driver interrupt handlers which are not prepared to handle a spurious interrupt correctly. This not a regression, it's just exposing something which was already broken as spurious interrupts can happen for a lot of reasons and all driver handlers need to be able to deal with them. Reported-by: Evan Green Debugged-by: Evan Green Signed-off-by: Thomas Gleixner Tested-by: Evan Green Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/87imkr4s7n.fsf@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman

KVM: Use vcpu-specific gva->hva translation when querying host page size

2020-02-11T12:34:17+00:00

[ Upstream commit f9b84e19221efc5f493156ee0329df3142085f28 ] Use kvm_vcpu_gfn_to_hva() when retrieving the host page size so that the correct set of memslots is used when handling x86 page faults in SMM. Fixes: 54bf36aac520 ("KVM: x86: use vcpu-specific functions to read/write/translate GFNs") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: nVMX: vmread should not set rflags to specify success in case of #PF

2020-02-11T12:34:17+00:00

[ Upstream commit a4d956b9390418623ae5d07933e2679c68b6f83c ] In case writing to vmread destination operand result in a #PF, vmread should not call nested_vmx_succeed() to set rflags to specify success. Similar to as done in VMPTRST (See handle_vmptrst()). Reviewed-by: Liran Alon Signed-off-by: Miaohe Lin Cc: stable@vger.kernel.org Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: VMX: Add non-canonical check on writes to RTIT address MSRs

2020-02-11T12:34:17+00:00

[ Upstream commit fe6ed369fca98e99df55c932b85782a5687526b5 ] Reject writes to RTIT address MSRs if the data being written is a non-canonical address as the MSRs are subject to canonical checks, e.g. KVM will trigger an unchecked #GP when loading the values to hardware during pt_guest_enter(). Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: x86: Use gpa_t for cr2/gpa to fix TDP support on 32-bit KVM

2020-02-11T12:34:17+00:00

[ Upstream commit 736c291c9f36b07f8889c61764c28edce20e715d ] Convert a plethora of parameters and variables in the MMU and page fault flows from type gva_t to gpa_t to properly handle TDP on 32-bit KVM. Thanks to PSE and PAE paging, 32-bit kernels can access 64-bit physical addresses. When TDP is enabled, the fault address is a guest physical address and thus can be a 64-bit value, even when both KVM and its guest are using 32-bit virtual addressing, e.g. VMX's VMCS.GUEST_PHYSICAL is a 64-bit field, not a natural width field. Using a gva_t for the fault address means KVM will incorrectly drop the upper 32-bits of the GPA. Ditto for gva_to_gpa() when it is used to translate L2 GPAs to L1 GPAs. Opportunistically rename variables and parameters to better reflect the dual address modes, e.g. use "cr2_or_gpa" for fault addresses and plain "addr" instead of "vaddr" when the address may be either a GVA or an L2 GPA. Similarly, use "gpa" in the nonpaging_page_fault() flows to avoid a confusing "gpa_t gva" declaration; this also sets the stage for a future patch to combing nonpaging_page_fault() and tdp_page_fault() with minimal churn. Sprinkle in a few comments to document flows where an address is known to be a GVA and thus can be safely truncated to a 32-bit value. Add WARNs in kvm_handle_page_fault() and FNAME(gva_to_gpa_nested)() to help document such cases and detect bugs. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: x86/mmu: Apply max PA check for MMIO sptes to 32-bit KVM

2020-02-11T12:34:17+00:00

[ Upstream commit e30a7d623dccdb3f880fbcad980b0cb589a1da45 ] Remove the bogus 64-bit only condition from the check that disables MMIO spte optimization when the system supports the max PA, i.e. doesn't have any reserved PA bits. 32-bit KVM always uses PAE paging for the shadow MMU, and per Intel's SDM: PAE paging translates 32-bit linear addresses to 52-bit physical addresses. The kernel's restrictions on max physical addresses are limits on how much memory the kernel can reasonably use, not what physical addresses are supported by hardware. Fixes: ce88decffd17 ("KVM: MMU: mmio page fault support") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

powerpc/44x: Adjust indentation in ibm4xx_denali_fixup_memsize

2020-02-11T12:34:12+00:00

commit c3aae14e5d468d18dbb5d7c0c8c7e2968cc14aad upstream. Clang warns: ../arch/powerpc/boot/4xx.c:231:3: warning: misleading indentation; statement is not part of the previous 'else' [-Wmisleading-indentation] val = SDRAM0_READ(DDR0_42); ^ ../arch/powerpc/boot/4xx.c:227:2: note: previous statement is here else ^ This is because there is a space at the beginning of this line; remove it so that the indentation is consistent according to the Linux kernel coding style and clang no longer warns. Fixes: d23f5099297c ("[POWERPC] 4xx: Adds decoding of 440SPE memory size to boot wrapper library") Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Michael Ellerman Link: https://github.com/ClangBuiltLinux/linux/issues/780 Link: https://lore.kernel.org/r/20191209200338.12546-1-natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman

KVM: s390: do not clobber registers during guest reset/store status

2020-02-11T12:34:11+00:00

commit 55680890ea78be0df5e1384989f1be835043c084 upstream. The initial CPU reset clobbers the userspace fpc and the store status ioctl clobbers the guest acrs + fpr. As these calls are only done via ioctl (and not via vcpu_run), no CPU context is loaded, so we can (and must) act directly on the sync regs, not on the thread context. Cc: stable@kernel.org Fixes: e1788bb995be ("KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load") Fixes: 31d8b8d41a7e ("KVM: s390: handle access registers in the run ioctl not in vcpu_put/load") Signed-off-by: Christian Borntraeger Reviewed-by: David Hildenbrand Reviewed-by: Cornelia Huck Signed-off-by: Janosch Frank Link: https://lore.kernel.org/r/20200131100205.74720-2-frankja@linux.ibm.com Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman

KVM: x86: Free wbinvd_dirty_mask if vCPU creation fails

2020-02-11T12:34:11+00:00

commit 16be9ddea268ad841457a59109963fff8c9de38d upstream. Free the vCPU's wbinvd_dirty_mask if vCPU creation fails after kvm_arch_vcpu_init(), e.g. when installing the vCPU's file descriptor. Do the freeing by calling kvm_arch_vcpu_free() instead of open coding the freeing. This adds a likely superfluous, but ultimately harmless, call to kvmclock_reset(), which only clears vcpu->arch.pv_time_enabled. Using kvm_arch_vcpu_free() allows for additional cleanup in the future. Fixes: f5f48ee15c2ee ("KVM: VMX: Execute WBINVD to keep data consistency with assigned devices") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: x86: Don't let userspace set host-reserved cr4 bits

2020-02-11T12:34:11+00:00

commit b11306b53b2540c6ba068c4deddb6a17d9f8d95b upstream. Calculate the host-reserved cr4 bits at runtime based on the system's capabilities (using logic similar to __do_cpuid_func()), and use the dynamically generated mask for the reserved bit check in kvm_set_cr4() instead using of the static CR4_RESERVED_BITS define. This prevents userspace from "enabling" features in cr4 that are not supported by the system, e.g. by ignoring KVM_GET_SUPPORTED_CPUID and specifying a bogus CPUID for the vCPU. Allowing userspace to set unsupported bits in cr4 can lead to a variety of undesirable behavior, e.g. failed VM-Enter, and in general increases KVM's attack surface. A crafty userspace can even abuse CR4.LA57 to induce an unchecked #GP on a WRMSR. On a platform without LA57 support: KVM_SET_CPUID2 // CPUID_7_0_ECX.LA57 = 1 KVM_SET_SREGS // CR4.LA57 = 1 KVM_SET_MSRS // KERNEL_GS_BASE = 0x0004000000000000 KVM_RUN leads to a #GP when writing KERNEL_GS_BASE into hardware: unchecked MSR access error: WRMSR to 0xc0000102 (tried to write 0x0004000000000000) at rIP: 0xffffffffa00f239a (vmx_prepare_switch_to_guest+0x10a/0x1d0 [kvm_intel]) Call Trace: kvm_arch_vcpu_ioctl_run+0x671/0x1c70 [kvm] kvm_vcpu_ioctl+0x36b/0x5d0 [kvm] do_vfs_ioctl+0xa1/0x620 ksys_ioctl+0x66/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x4c/0x170 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fc08133bf47 Note, the above sequence fails VM-Enter due to invalid guest state. Userspace can allow VM-Enter to succeed (after the WRMSR #GP) by adding a KVM_SET_SREGS w/ CR4.LA57=0 after KVM_SET_MSRS, in which case KVM will technically leak the host's KERNEL_GS_BASE into the guest. But, as KERNEL_GS_BASE is a userspace-defined value/address, the leak is largely benign as a malicious userspace would simply be exposing its own data to the guest, and attacking a benevolent userspace would require multiple bugs in the userspace VMM. Cc: stable@vger.kernel.org Cc: Jun Nakajima Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman