linux-kernel - Re: [RFC PATCH 07/21] KVM: TDX: Add a helper for WBINVD on huge pages with TD's keyID

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <40898a3dc6637f89b59c309d471d9f4a8f417a9e.camel@intel.com>
Date: Tue, 13 May 2025 19:29:00 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>, "Zhao, Yan Y" <yan.y.zhao@...el.com>
CC: "Shutemov, Kirill" <kirill.shutemov@...el.com>, "quic_eberman@...cinc.com"
	<quic_eberman@...cinc.com>, "Li, Xiaoyao" <xiaoyao.li@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>, "Hansen, Dave"
	<dave.hansen@...el.com>, "david@...hat.com" <david@...hat.com>,
	"thomas.lendacky@....com" <thomas.lendacky@....com>, "tabba@...gle.com"
	<tabba@...gle.com>, "Li, Zhiquan1" <zhiquan1.li@...el.com>, "Du, Fan"
	<fan.du@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "michael.roth@....com"
	<michael.roth@....com>, "Weiny, Ira" <ira.weiny@...el.com>, "vbabka@...e.cz"
	<vbabka@...e.cz>, "binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>,
	"ackerleytng@...gle.com" <ackerleytng@...gle.com>, "Yamahata, Isaku"
	<isaku.yamahata@...el.com>, "Peng, Chao P" <chao.p.peng@...el.com>,
	"Annapurve, Vishal" <vannapurve@...gle.com>, "jroedel@...e.de"
	<jroedel@...e.de>, "Miao, Jun" <jun.miao@...el.com>, "pgonda@...gle.com"
	<pgonda@...gle.com>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [RFC PATCH 07/21] KVM: TDX: Add a helper for WBINVD on huge pages
 with TD's keyID

On Thu, 2025-04-24 at 11:05 +0800, Yan Zhao wrote:
> From: Xiaoyao Li <xiaoyao.li@...el.com>
> 
> After a guest page is removed from the S-EPT, KVM calls
> tdh_phymem_page_wbinvd_hkid() to execute WBINVD on the page using the TD's
> keyID.
> 
> Add a helper function that takes level information to perform WBINVD on a
> huge page.
> 
> [Yan: split patch, added a helper, rebased to use struct page]
> Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> ---
>  arch/x86/kvm/vmx/tdx.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 69f3140928b5..355b21fc169f 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1586,6 +1586,23 @@ int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
>  	return tdx_mem_page_record_premap_cnt(kvm, level);
>  }
>  
> +static inline u64 tdx_wbinvd_page(struct kvm *kvm, u64 hkid, struct page *page, int level)
> +{
> +	unsigned long nr = KVM_PAGES_PER_HPAGE(level);
> +	unsigned long idx = 0;
> +	u64 err;
> +
> +	while (nr--) {
> +		err = tdh_phymem_page_wbinvd_hkid(hkid, nth_page(page, idx++));
> +
> +		if (KVM_BUG_ON(err, kvm)) {
> +			pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
> +			return err;
> +		}
> +	}
> +	return err;
> +}

Hmm, did you consider changing tdh_phymem_page_wbinvd_hkid()? It's the pattern
of KVM wrapping the SEAMCALL helpers to do some more work that needs to be
wrapped.

> +
>  static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
>  				      enum pg_level level, struct page *page)
>  {
> @@ -1625,12 +1642,9 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
>  		return -EIO;
>  	}
>  
> -	err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, page);
> -
> -	if (KVM_BUG_ON(err, kvm)) {
> -		pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
> +	err = tdx_wbinvd_page(kvm, kvm_tdx->hkid, page, level);
> +	if (err)
>  		return -EIO;
> -	}
>  
>  	tdx_clear_page(page, level);
>  	tdx_unpin(kvm, page);