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X-CSE-ConnectionGUID: HctYq7DBR3GsMi1vt0YYFQ== X-CSE-MsgGUID: 20PMjCc8QOSIUNPWYN65Pw== X-IronPort-AV: E=McAfee;i="6700,10204,11287"; a="22270610" X-IronPort-AV: E=Sophos;i="6.12,237,1728975600"; d="scan'208";a="22270610" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Dec 2024 17:14:17 -0800 X-CSE-ConnectionGUID: /TW0921wQhqXpaMWjUT1dQ== X-CSE-MsgGUID: ldYB+vS2RYa5Q/UOsBmSrA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="101623199" Received: from unknown (HELO [10.238.9.154]) ([10.238.9.154]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Dec 2024 17:14:14 -0800 Message-ID: <82a916da-0053-46c6-abfe-faf170cb5a8c@linux.intel.com> Date: Mon, 16 Dec 2024 09:14:11 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/7] KVM: TDX: Handle TDG.VP.VMCALL To: Xiaoyao Li Cc: pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org, rick.p.edgecombe@intel.com, kai.huang@intel.com, adrian.hunter@intel.com, reinette.chatre@intel.com, tony.lindgren@linux.intel.com, isaku.yamahata@intel.com, yan.y.zhao@intel.com, chao.gao@intel.com, michael.roth@amd.com, linux-kernel@vger.kernel.org References: <20241201035358.2193078-1-binbin.wu@linux.intel.com> <20241201035358.2193078-6-binbin.wu@linux.intel.com> Content-Language: en-US From: Binbin Wu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/13/2024 5:40 PM, Xiaoyao Li wrote: > On 12/1/2024 11:53 AM, Binbin Wu wrote: >> Convert TDG.VP.VMCALL to KVM_EXIT_SYSTEM_EVENT with >> a new type KVM_SYSTEM_EVENT_TDX_FATAL and forward it to userspace for >> handling. >> >> TD guest can use TDG.VP.VMCALL to report the fatal >> error it has experienced.  This hypercall is special because TD guest >> is requesting a termination with the error information, KVM needs to >> forward the hypercall to userspace anyway, KVM doesn't do sanity checks >> and let userspace decide what to do. >> >> Signed-off-by: Binbin Wu >> --- >> Hypercalls exit to userspace breakout: >> - New added. >>    Implement one of the hypercalls need to exit to userspace for handling after >>    reverting "KVM: TDX: Add KVM Exit for TDX TDG.VP.VMCALL", which tries to resolve >>    Sean's comment. >>    https://lore.kernel.org/kvm/Zg18ul8Q4PGQMWam@google.com/ >> - Use TDVMCALL_STATUS prefix for TDX call status codes (Binbin) >> --- >>   Documentation/virt/kvm/api.rst |  8 ++++++ >>   arch/x86/kvm/vmx/tdx.c         | 50 ++++++++++++++++++++++++++++++++++ >>   include/uapi/linux/kvm.h       |  1 + >>   3 files changed, 59 insertions(+) >> >> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst >> index edc070c6e19b..bb39da72c647 100644 >> --- a/Documentation/virt/kvm/api.rst >> +++ b/Documentation/virt/kvm/api.rst >> @@ -6815,6 +6815,7 @@ should put the acknowledged interrupt vector into the 'epr' field. >>     #define KVM_SYSTEM_EVENT_WAKEUP         4 >>     #define KVM_SYSTEM_EVENT_SUSPEND        5 >>     #define KVM_SYSTEM_EVENT_SEV_TERM       6 >> +  #define KVM_SYSTEM_EVENT_TDX_FATAL      7 >>               __u32 type; >>                           __u32 ndata; >>                           __u64 data[16]; >> @@ -6841,6 +6842,13 @@ Valid values for 'type' are: >>      reset/shutdown of the VM. >>    - KVM_SYSTEM_EVENT_SEV_TERM -- an AMD SEV guest requested termination. >>      The guest physical address of the guest's GHCB is stored in `data[0]`. >> + - KVM_SYSTEM_EVENT_TDX_FATAL -- an TDX guest requested termination. >> +   The error codes of the guest's GHCI is stored in `data[0]`. >> +   If the bit 63 of `data[0]` is set, it indicates there is TD specified >> +   additional information provided in a page, which is shared memory. The >> +   guest physical address of the information page is stored in `data[1]`. >> +   An optional error message is provided by `data[2]` ~ `data[9]`, which is >> +   byte sequence, LSB filled first. Typically, ASCII code(0x20-0x7e) is filled. >>    - KVM_SYSTEM_EVENT_WAKEUP -- the exiting vCPU is in a suspended state and >>      KVM has recognized a wakeup event. Userspace may honor this event by >>      marking the exiting vCPU as runnable, or deny it and call KVM_RUN again. >> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c >> index 553f4cbe0693..a79f9ca962d1 100644 >> --- a/arch/x86/kvm/vmx/tdx.c >> +++ b/arch/x86/kvm/vmx/tdx.c >> @@ -1093,6 +1093,54 @@ static int tdx_map_gpa(struct kvm_vcpu *vcpu) >>       return 1; >>   } >>   +static int tdx_report_fatal_error(struct kvm_vcpu *vcpu) >> +{ >> +    u64 reg_mask = kvm_rcx_read(vcpu); >> +    u64* opt_regs; >> + >> +    /* >> +     * Skip sanity checks and let userspace decide what to do if sanity >> +     * checks fail. >> +     */ >> +    vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT; >> +    vcpu->run->system_event.type = KVM_SYSTEM_EVENT_TDX_FATAL; >> +    vcpu->run->system_event.ndata = 10; >> +    /* Error codes. */ >> +    vcpu->run->system_event.data[0] = tdvmcall_a0_read(vcpu); >> +    /* GPA of additional information page. */ >> +    vcpu->run->system_event.data[1] = tdvmcall_a1_read(vcpu); >> +    /* Information passed via registers (up to 64 bytes). */ >> +    opt_regs = &vcpu->run->system_event.data[2]; >> + >> +#define COPY_REG(REG, MASK)                        \ >> +    do {                                \ >> +        if (reg_mask & MASK)                    \ >> +            *opt_regs = kvm_ ## REG ## _read(vcpu);        \ >> +        else                            \ >> +            *opt_regs = 0;                    \ >> +        opt_regs++;                        \ > > I'm not sure if we need to skip the "opt_regs++" the corresponding register is not set valid in reg_mask. And maintain ndata to actual valid number instead of hardcoding it to 10. Yes, it's better. > >> +    } while (0) >> + >> +    /* The order is defined in GHCI. */ >> +    COPY_REG(r14, BIT_ULL(14)); >> +    COPY_REG(r15, BIT_ULL(15)); >> +    COPY_REG(rbx, BIT_ULL(3)); >> +    COPY_REG(rdi, BIT_ULL(7)); >> +    COPY_REG(rsi, BIT_ULL(6)); >> +    COPY_REG(r8, BIT_ULL(8)); >> +    COPY_REG(r9, BIT_ULL(9)); >> +    COPY_REG(rdx, BIT_ULL(2)); >> + >> +    /* >> +     * Set the status code according to GHCI spec, although the vCPU may >> +     * not return back to guest. >> +     */ >> +    tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_SUCCESS); >> + >> +    /* Forward request to userspace. */ >> +    return 0; >> +} >> + >>   static int handle_tdvmcall(struct kvm_vcpu *vcpu) >>   { >>       if (tdvmcall_exit_type(vcpu)) >> @@ -1101,6 +1149,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu) >>       switch (tdvmcall_leaf(vcpu)) { >>       case TDVMCALL_MAP_GPA: >>           return tdx_map_gpa(vcpu); >> +    case TDVMCALL_REPORT_FATAL_ERROR: >> +        return tdx_report_fatal_error(vcpu); >>       default: >>           break; >>       } >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >> index 637efc055145..c173c8dfcf83 100644 >> --- a/include/uapi/linux/kvm.h >> +++ b/include/uapi/linux/kvm.h >> @@ -375,6 +375,7 @@ struct kvm_run { >>   #define KVM_SYSTEM_EVENT_WAKEUP         4 >>   #define KVM_SYSTEM_EVENT_SUSPEND        5 >>   #define KVM_SYSTEM_EVENT_SEV_TERM       6 >> +#define KVM_SYSTEM_EVENT_TDX_FATAL      7 >>               __u32 type; >>               __u32 ndata; >>               union { > >