From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3288E2F25 for ; Mon, 7 Feb 2022 22:03:57 +0000 (UTC) Received: by mail-pf1-f170.google.com with SMTP id e28so15398571pfj.5 for ; Mon, 07 Feb 2022 14:03:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UPy7lygPxr90ipECLkuZI1hGfjCl5QQ8FuHy0YowhSc=; b=RCgXhswVoMfKJgmEInLACfKtrGVLqOCKWZNQ41sxN5QDiS7VwL/G07y2oU0WB8ztNR Y0S/kH1ShxVpYYabvAnlMUsDkJFODoyyY5dzhb1Fd7mnBLqXM9Rec01w4aj7PGNdeL5n RWuK3IpF25Z9D8lhRsyEZAKgCsMiGAZNHpKo086hki4ByVDihSrUinUl2fJl0XC9tujL PNBkTL6RuaWSjX1S5vLoYvoof4pfeRaDyEpdC+mVVVIu7XPHvEn4en4/Y4pIL4hV6rr1 Cdy78LZyRztbpdzjvMGH8T8h9AbVd0QzBozwz2j0qazz4F8EmAc5xBhZNFYgkPpM1Tn/ gMUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UPy7lygPxr90ipECLkuZI1hGfjCl5QQ8FuHy0YowhSc=; b=lBzle+kDpNsrkv86PDy86fuQbfixAapHAI9DfwUv0/QYUqm9j2uOV5d2Dxwyx2lFal Jm9TrWrVXe83uUryVXqPxRZwiUcDxBa4Ebh57E+1jp9bAJeCwv/m2R0VjR+FG28+vjZY V4YiJLr24fttbnx83cCuekMqY49og84p1pakzdvPSnoTuYwk83pdUErz1otE8Hmt3RUa HHNCdhQ5vFQGLWjF01DzuXjNuSraoJxyiOzAn4POpdgf4B4pIOszeA1gt7vho0w6dccl tYKNABOKVX5ReH3C+bBceia2KIsIfzXajUuo+28C0rBCGKnyV7YRKncyfYtJL4E4tHft Dqeg== X-Gm-Message-State: AOAM533+K0XHvwRL6veNsRJq1sRs06gZ1J+nfgJrGv9WnpPu7NyVtLOC z5fqUlSobkx8eppbFVk17DU1gw== X-Google-Smtp-Source: ABdhPJzbBC9XPXZx1a7sY7aumuFcnEQRXSeGjArZY3492Wqxxm+qGn6UVim4VyXN7pLekEvoM53jAg== X-Received: by 2002:a63:2c83:: with SMTP id s125mr1103589pgs.265.1644271436434; Mon, 07 Feb 2022 14:03:56 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id q2sm13779245pfj.94.2022.02.07.14.03.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Feb 2022 14:03:55 -0800 (PST) Date: Mon, 7 Feb 2022 22:03:52 +0000 From: Sean Christopherson To: Joerg Roedel Cc: x86@kernel.org, Joerg Roedel , Eric Biederman , kexec@lists.infradead.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v3 04/10] x86/sev: Cache AP Jump Table Address Message-ID: References: <20220127101044.13803-1-joro@8bytes.org> <20220127101044.13803-5-joro@8bytes.org> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220127101044.13803-5-joro@8bytes.org> On Thu, Jan 27, 2022, Joerg Roedel wrote: > From: Joerg Roedel > > Store the physical address of the AP jump table in kernel memory so > that it does not need to be fetched from the Hypervisor again. This doesn't explain why the kernel would retrieve the jump table more than once, e.g. at this point in the series, this can only ever be called once. > Signed-off-by: Joerg Roedel > --- > arch/x86/kernel/sev.c | 28 +++++++++++++++------------- > 1 file changed, 15 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index 8a4317fa699a..969ef9855bb5 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -43,6 +43,9 @@ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); > */ > static struct ghcb __initdata *boot_ghcb; > > +/* Cached AP jump table Address */ > +static phys_addr_t jump_table_pa; > + > /* #VC handler runtime per-CPU data */ > struct sev_es_runtime_data { > struct ghcb ghcb_page; > @@ -523,12 +526,14 @@ void noinstr __sev_es_nmi_complete(void) > __sev_put_ghcb(&state); > } > > -static u64 get_jump_table_addr(void) > +static phys_addr_t get_jump_table_addr(void) Not new, but I believe this can be tagged __init. > { > struct ghcb_state state; > unsigned long flags; > struct ghcb *ghcb; > - u64 ret = 0; > + > + if (jump_table_pa) > + return jump_table_pa; > > local_irq_save(flags); > > @@ -544,39 +549,36 @@ static u64 get_jump_table_addr(void) > > if (ghcb_sw_exit_info_1_is_valid(ghcb) && > ghcb_sw_exit_info_2_is_valid(ghcb)) > - ret = ghcb->save.sw_exit_info_2; > + jump_table_pa = (phys_addr_t)ghcb->save.sw_exit_info_2; > > __sev_put_ghcb(&state); > > local_irq_restore(flags); > > - return ret; > + return jump_table_pa; > } > > int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) __init here too. > { > u16 startup_cs, startup_ip; > - phys_addr_t jump_table_pa; > - u64 jump_table_addr; > u16 __iomem *jump_table; > + phys_addr_t pa; > > - jump_table_addr = get_jump_table_addr(); > + pa = get_jump_table_addr(); > > /* On UP guests there is no jump table so this is not a failure */ Does anything actually check that the jump table is valid for SMP guests? > - if (!jump_table_addr) > + if (!pa) Using '0' for "not valid" is funky because '0' isn't technically an illegal GPA, and because it means the address (or lack thereof) isn't cached on a single-vCPU guest.