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Sun, 16 Feb 2025 10:26:36 -0800 (PST) Received: from [192.168.10.48] ([176.206.122.109]) by smtp.googlemail.com with ESMTPSA id ffacd0b85a97d-38f258f5efdsm10053303f8f.43.2025.02.16.10.26.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 16 Feb 2025 10:26:36 -0800 (PST) Message-ID: <0c2bb665-93ee-4f46-ac28-5dbd1dd2b9a2@redhat.com> Date: Sun, 16 Feb 2025 19:26:34 +0100 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 V2 01/12] x86/virt/tdx: Make tdh_vp_enter() noinstr To: Adrian Hunter , seanjc@google.com Cc: kvm@vger.kernel.org, rick.p.edgecombe@intel.com, kai.huang@intel.com, reinette.chatre@intel.com, xiaoyao.li@intel.com, tony.lindgren@linux.intel.com, binbin.wu@linux.intel.com, dmatlack@google.com, isaku.yamahata@intel.com, nik.borisov@suse.com, linux-kernel@vger.kernel.org, yan.y.zhao@intel.com, chao.gao@intel.com, weijiang.yang@intel.com, dave.hansen@linux.intel.com, x86@kernel.org References: <20250129095902.16391-1-adrian.hunter@intel.com> <20250129095902.16391-2-adrian.hunter@intel.com> From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/29/25 10:58, Adrian Hunter wrote: > Make tdh_vp_enter() noinstr because KVM requires VM entry to be noinstr > for 2 reasons: > 1. The use of context tracking via guest_state_enter_irqoff() and > guest_state_exit_irqoff() > 2. The need to avoid IRET between VM-exit and NMI handling in order to > avoid prematurely releasing NMI inhibit. > > Consequently make __seamcall_saved_ret() noinstr also. Currently > tdh_vp_enter() is the only caller of __seamcall_saved_ret(). > > Signed-off-by: Adrian Hunter This can be squashed into "x86/virt/tdx: Add SEAMCALL wrapper to enter/exit TDX guest"; I did that in kvm-coco-queue. Paolo > --- > TD vcpu enter/exit v2: > - New patch > --- > arch/x86/virt/vmx/tdx/seamcall.S | 3 +++ > arch/x86/virt/vmx/tdx/tdx.c | 2 +- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/virt/vmx/tdx/seamcall.S b/arch/x86/virt/vmx/tdx/seamcall.S > index 5b1f2286aea9..6854c52c374b 100644 > --- a/arch/x86/virt/vmx/tdx/seamcall.S > +++ b/arch/x86/virt/vmx/tdx/seamcall.S > @@ -41,6 +41,9 @@ SYM_FUNC_START(__seamcall_ret) > TDX_MODULE_CALL host=1 ret=1 > SYM_FUNC_END(__seamcall_ret) > > +/* KVM requires non-instrumentable __seamcall_saved_ret() for TDH.VP.ENTER */ > +.section .noinstr.text, "ax" > + > /* > * __seamcall_saved_ret() - Host-side interface functions to SEAM software > * (the P-SEAMLDR or the TDX module), with saving output registers to the > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c > index 4a010e65276d..1515c467dd86 100644 > --- a/arch/x86/virt/vmx/tdx/tdx.c > +++ b/arch/x86/virt/vmx/tdx/tdx.c > @@ -1511,7 +1511,7 @@ static void tdx_clflush_page(struct page *page) > clflush_cache_range(page_to_virt(page), PAGE_SIZE); > } > > -u64 tdh_vp_enter(struct tdx_vp *td, struct tdx_module_args *args) > +noinstr u64 tdh_vp_enter(struct tdx_vp *td, struct tdx_module_args *args) > { > args->rcx = tdx_tdvpr_pa(td); >