kernel/linux.git/arch/powerpc/kvm, branch linux-4.4.y

KVM: PPC: Book3S: Fix H_RTAS rets buffer overflow

2021-07-28T07:12:36+00:00

commit f62f3c20647ebd5fb6ecb8f0b477b9281c44c10a upstream. The kvmppc_rtas_hcall() sets the host rtas_args.rets pointer based on the rtas_args.nargs that was provided by the guest. That guest nargs value is not range checked, so the guest can cause the host rets pointer to be pointed outside the args array. The individual rtas function handlers check the nargs and nrets values to ensure they are correct, but if they are not, the handlers store a -3 (0xfffffffd) failure indication in rets[0] which corrupts host memory. Fix this by testing up front whether the guest supplied nargs and nret would exceed the array size, and fail the hcall directly without storing a failure indication to rets[0]. Also expand on a comment about why we kill the guest and try not to return errors directly if we have a valid rets[0] pointer. Fixes: 8e591cb72047 ("KVM: PPC: Book3S: Add infrastructure to implement kernel-side RTAS calls") Cc: stable@vger.kernel.org # v3.10+ Reported-by: Alexey Kardashevskiy Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S PR: Free shared page if mmu initialization fails

2020-02-14T21:29:58+00:00

commit cb10bf9194f4d2c5d830eddca861f7ca0fecdbb4 upstream. Explicitly free the shared page if kvmppc_mmu_init() fails during kvmppc_core_vcpu_create(), as the page is freed only in kvmppc_core_vcpu_free(), which is not reached via kvm_vcpu_uninit(). Fixes: 96bc451a15329 ("KVM: PPC: Introduce shared page") Cc: stable@vger.kernel.org Reviewed-by: Greg Kurz Signed-off-by: Sean Christopherson Acked-by: Paul Mackerras Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S HV: Uninit vCPU if vcore creation fails

2020-02-14T21:29:58+00:00

commit 1a978d9d3e72ddfa40ac60d26301b154247ee0bc upstream. Call kvm_vcpu_uninit() if vcore creation fails to avoid leaking any resources allocated by kvm_vcpu_init(), i.e. the vcpu->run page. Fixes: 371fefd6f2dc4 ("KVM: PPC: Allow book3s_hv guests to use SMT processor modes") Cc: stable@vger.kernel.org Reviewed-by: Greg Kurz Signed-off-by: Sean Christopherson Acked-by: Paul Mackerras Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S HV: Flush link stack on guest exit to host kernel

2019-11-28T17:26:29+00:00

commit af2e8c68b9c5403f77096969c516f742f5bb29e0 upstream. On some systems that are vulnerable to Spectre v2, it is up to software to flush the link stack (return address stack), in order to protect against Spectre-RSB. When exiting from a guest we do some house keeping and then potentially exit to C code which is several stack frames deep in the host kernel. We will then execute a series of returns without preceeding calls, opening up the possiblity that the guest could have poisoned the link stack, and direct speculative execution of the host to a gadget of some sort. To prevent this we add a flush of the link stack on exit from a guest. Signed-off-by: Michael Ellerman [dja: backport to v4.4, drop P9 support] Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S PR: Exiting split hack mode needs to fixup both PC and LR

2019-11-25T14:54:39+00:00

[ Upstream commit 1006284c5e411872333967b1970c2ca46a9e225f ] When an OS (currently only classic Mac OS) is running in KVM-PR and makes a linked jump from code with split hack addressing enabled into code that does not, LR is not correctly updated and reflects the previously munged PC. To fix this, this patch undoes the address munge when exiting split hack mode so that code relying on LR being a proper address will now execute. This does not affect OS X or other operating systems running on KVM-PR. Signed-off-by: Cameron Kaiser Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

KVM: PPC: Book3S: Use new mutex to synchronize access to rtas token list

2019-06-22T06:18:26+00:00

[ Upstream commit 1659e27d2bc1ef47b6d031abe01b467f18cb72d9 ] Currently the Book 3S KVM code uses kvm->lock to synchronize access to the kvm->arch.rtas_tokens list. Because this list is scanned inside kvmppc_rtas_hcall(), which is called with the vcpu mutex held, taking kvm->lock cause a lock inversion problem, which could lead to a deadlock. To fix this, we add a new mutex, kvm->arch.rtas_token_lock, which nests inside the vcpu mutexes, and use that instead of kvm->lock when accessing the rtas token list. This removes the lockdep_assert_held() in kvmppc_rtas_tokens_free(). At this point we don't hold the new mutex, but that is OK because kvmppc_rtas_tokens_free() is only called when the whole VM is being destroyed, and at that point nothing can be looking up a token in the list. Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin

powerpc/fsl: Emulate SPRN_BUCSR register

2019-05-16T17:44:53+00:00

commit 98518c4d8728656db349f875fcbbc7c126d4c973 upstream. In order to flush the branch predictor the guest kernel performs writes to the BUCSR register which is hypervisor privilleged. However, the branch predictor is flushed at each KVM entry, so the branch predictor has been already flushed, so just return as soon as possible to guest. Signed-off-by: Diana Craciun [mpe: Tweak comment formatting] Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/fsl: Flush branch predictor when entering KVM

2019-05-16T17:44:53+00:00

commit e7aa61f47b23afbec41031bc47ca8d6cb6516abc upstream. Switching from the guest to host is another place where the speculative accesses can be exploited. Flush the branch predictor when entering KVM. Signed-off-by: Diana Craciun Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Move and undef TRACE_INCLUDE_PATH/FILE

2018-12-01T08:46:34+00:00

[ Upstream commit 28c5bcf74fa07c25d5bd118d1271920f51ce2a98 ] TRACE_INCLUDE_PATH and TRACE_INCLUDE_FILE are used by , so like that #include, they should be outside #ifdef protection. They also need to be #undefed before defining, in case multiple trace headers are included by the same C file. This became the case on book3e after commit cf4a6085151a ("powerpc/mm: Add missing tracepoint for tlbie"), leading to the following build error: CC arch/powerpc/kvm/powerpc.o In file included from arch/powerpc/kvm/powerpc.c:51:0: arch/powerpc/kvm/trace.h:9:0: error: "TRACE_INCLUDE_PATH" redefined [-Werror] #define TRACE_INCLUDE_PATH . ^ In file included from arch/powerpc/kvm/../mm/mmu_decl.h:25:0, from arch/powerpc/kvm/powerpc.c:48: ./arch/powerpc/include/asm/trace.h:224:0: note: this is the location of the previous definition #define TRACE_INCLUDE_PATH asm ^ cc1: all warnings being treated as errors Reported-by: Christian Zigotzky Signed-off-by: Scott Wood Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin

KVM: PPC: Book3S HV: Don't truncate HPTE index in xlate function

2018-10-10T06:52:10+00:00

[ Upstream commit 46dec40fb741f00f1864580130779aeeaf24fb3d ] This fixes a bug which causes guest virtual addresses to get translated to guest real addresses incorrectly when the guest is using the HPT MMU and has more than 256GB of RAM, or more specifically has a HPT larger than 2GB. This has showed up in testing as a failure of the host to emulate doorbell instructions correctly on POWER9 for HPT guests with more than 256GB of RAM. The bug is that the HPTE index in kvmppc_mmu_book3s_64_hv_xlate() is stored as an int, and in forming the HPTE address, the index gets shifted left 4 bits as an int before being signed-extended to 64 bits. The simple fix is to make the variable a long int, matching the return type of kvmppc_hv_find_lock_hpte(), which is what calculates the index. Fixes: 697d3899dcb4 ("KVM: PPC: Implement MMIO emulation support for Book3S HV guests") Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman