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AHgh+Rr7iu6SRDmj5cClMRHdZLwPYrb/PJAxzTFtMFQ+aaMIZl4Qi6WtqOh/+wbclsMsl8zEo205viZbgXpV@lists.linux.dev X-Gm-Message-State: AFuF++nD5s9faOU68e54oa7P2O0n7K7wdcR/hbcmeiRTt5fT3CUgy5zl S0sI6d6akIcbzh2SbPiFpOkVaju10oSiCRmRHw8R/KPrCe34oCTh58oKmQYvDjZxIiX+ZB6XBvw dzYafqg== X-Received: from pgch31.prod.google.com ([2002:a05:6a02:509f:b0:c9e:3c0b:5818]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:134b:b0:3c4:396d:4a6c with SMTP id adf61e73a8af0-3cd910a2c53mr15074204637.5.1787664680841; Tue, 25 Aug 2026 06:31:20 -0700 (PDT) Date: Tue, 25 Aug 2026 06:31:11 -0700 In-Reply-To: <20260825025533.25663-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260825025533.25663-1-yan.y.zhao@intel.com> Message-ID: Subject: Re: [PATCH] x86/virt/tdx: Warn on !4K level in tdh_mem_page_aug() From: Sean Christopherson To: Yan Zhao Cc: kas@kernel.org, dave.hansen@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, rick.p.edgecombe@intel.com, pbonzini@redhat.com, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, kai.huang@intel.com, yilun.xu@linux.intel.com, vannapurve@google.com, ackerleytng@google.com, sagis@google.com, binbin.wu@linux.intel.com, xiaoyao.li@intel.com, Dave Hansen Content-Type: text/plain; charset="us-ascii" On Tue, Aug 25, 2026, Yan Zhao wrote: > Add a warning on a !4K level to loudly flag the unexpected condition when > callers pass in a level > 4K before tdh_mem_page_aug() supports huge pages. > > The warning makes the unexpected condition more obvious since the SEAMCALL > TDH_MEM_PAGE_AUG does not necessarily fail when the level is above 4K, > while tdh_mem_page_aug() only flushes the cache for a 4K page before huge > page support is added. If the only problem is the lack of CLFLUSH coverage, why not simply fix the bug? The changelog spends more effort justifying not fixing a bug than it would take to fix the bug. diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index 42df8ea464c4..1a83857eb7e6 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -1628,9 +1628,9 @@ static void tdx_clflush_page(struct page *page) clflush_cache_range(page_to_virt(page), PAGE_SIZE); } -static void tdx_clflush_pfn(kvm_pfn_t pfn) +static void tdx_clflush_pfn(kvm_pfn_t pfn, enum pg_level level) { - clflush_cache_range(__va(PFN_PHYS(pfn)), PAGE_SIZE); + clflush_cache_range(__va(PFN_PHYS(pfn)), page_level_size(level)); } static int pg_level_to_tdx_sept_level(enum pg_level level) @@ -1670,7 +1670,7 @@ u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, kvm_pfn_t pfn, struct page *sou }; u64 ret; - tdx_clflush_pfn(pfn); + tdx_clflush_pfn(pfn, PG_LEVEL_4K); ret = seamcall_ret(TDH_MEM_PAGE_ADD, &args); *ext_err1 = args.rcx; @@ -1722,7 +1722,7 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, enum pg_level level, }; u64 ret; - tdx_clflush_pfn(pfn); + tdx_clflush_pfn(pfn, level); ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args); *ext_err1 = args.rcx;