From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brijesh Singh Subject: Re: [PATCH v8 1/2] x86/mm: add .bss..decrypted section to hold shared variables Date: Thu, 13 Sep 2018 21:14:47 -0500 Message-ID: References: <1536875471-17391-1-git-send-email-brijesh.singh@amd.com> <1536875471-17391-2-git-send-email-brijesh.singh@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: brijesh.singh@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Tom Lendacky , Borislav Petkov , "H. Peter Anvin" , Paolo Bonzini , Sean Christopherson , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= To: Thomas Gleixner Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 9/13/18 6:24 PM, Thomas Gleixner wrote: > On Thu, 13 Sep 2018, Brijesh Singh wrote: >> >> +void __weak mem_encrypt_free_decrypted_mem(void) { } >> + >> void __ref free_initmem(void) >> { >> e820__reallocate_tables(); >> >> + mem_encrypt_free_decrypted_mem(); >> + >> free_kernel_image_pages(&__init_begin, &__init_end); >> } >> >> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c >> index b2de398..718acdf 100644 >> --- a/arch/x86/mm/mem_encrypt.c >> +++ b/arch/x86/mm/mem_encrypt.c >> @@ -348,6 +348,16 @@ bool sev_active(void) >> EXPORT_SYMBOL(sev_active); >> >> /* Architecture __weak replacement functions */ >> +void __init mem_encrypt_free_decrypted_mem(void) >> +{ >> + if (mem_encrypt_active()) >> + return; > Why? Hmm, I think we should be able to free the unused memory when memory encryption is active. In that case, since memory range was mapped C=0 so we should do set_memory_encryptyed() to change from C=0 -> C=1 before freeing it. >> + >> + free_init_pages("unused decrypted", >> + (unsigned long)__start_bss_decrypted_unused, >> + (unsigned long)__end_bss_decrypted); > Everything _AFTER_ __start_bss_decrypted_unused _IS_ unused and can be > freed. No conditional nothing. It's unused in any case. > > Thanks, > > tglx > >