From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sathyanarayanan Kuppuswamy Subject: Re: [PATCH v5 04/16] x86/tdx: Make pages shared in ioremap() Date: Wed, 20 Oct 2021 09:41:29 -0700 Message-ID: References: <20211009003711.1390019-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20211009003711.1390019-5-sathyanarayanan.kuppuswamy@linux.intel.com> <8c5074f7-5456-e628-5a09-a3a4b4f381fb@amd.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <8c5074f7-5456-e628-5a09-a3a4b4f381fb@amd.com> Content-Language: en-US List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: Tom Lendacky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , Bjorn Helgaas , Richard Henderson , Thomas Bogendoerfer , James E J Bottomley , Helge Deller , "David S . Miller" , Arnd Bergmann , Jonathan Corbet , "Michael S . Tsirkin" , Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Josh Poimboeuf Cc: Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , x86@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux-foundation.org On 10/20/21 9:03 AM, Tom Lendacky wrote: > On 10/8/21 7:36 PM, Kuppuswamy Sathyanarayanan wrote: >> From: "Kirill A. Shutemov" >> >> All ioremap()ed pages that are not backed by normal memory (NONE or >> RESERVED) have to be mapped as shared. >> >> Reuse the infrastructure from AMD SEV code. >> >> Note that DMA code doesn't use ioremap() to convert memory to shared as >> DMA buffers backed by normal memory. DMA code make buffer shared with >> set_memory_decrypted(). >> >> Signed-off-by: Kirill A. Shutemov >> Reviewed-by: Andi Kleen >> Reviewed-by: Tony Luck >> Signed-off-by: Kuppuswamy Sathyanarayanan >> >> --- >> >> Changes since v4: >>   * Renamed "protected_guest" to "cc_guest". >>   * Replaced use of prot_guest_has() with cc_guest_has() >>   * Modified the patch to adapt to latest version cc_guest_has() >>     changes. >> >> Changes since v3: >>   * Rebased on top of Tom Lendacky's protected guest >>     changes (https://lore.kernel.org/patchwork/cover/1468760/) >> >> Changes since v1: >>   * Fixed format issues in commit log. >> >>   arch/x86/include/asm/pgtable.h |  4 ++++ >>   arch/x86/mm/ioremap.c          |  8 ++++++-- >>   include/linux/cc_platform.h    | 13 +++++++++++++ >>   3 files changed, 23 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/include/asm/pgtable.h >> b/arch/x86/include/asm/pgtable.h >> index 448cd01eb3ec..ecefccbdf2e3 100644 >> --- a/arch/x86/include/asm/pgtable.h >> +++ b/arch/x86/include/asm/pgtable.h >> @@ -21,6 +21,10 @@ >>   #define pgprot_encrypted(prot)    __pgprot(__sme_set(pgprot_val(prot))) >>   #define pgprot_decrypted(prot)    __pgprot(__sme_clr(pgprot_val(prot))) >> +/* Make the page accesable by VMM for confidential guests */ >> +#define pgprot_cc_guest(prot) __pgprot(pgprot_val(prot) |    \ >> +                          tdx_shared_mask()) > > So this is only for TDX guests, so maybe a name that is less generic. > > Alternatively, you could create pgprot_private()/pgprot_shared() > functions that check for SME/SEV or TDX and do the proper thing. > > Then you can redefine pgprot_encrypted()/pgprot_decrypted() to the new > functions? Make sense. It will be a better abstraction. I will make this change in next version. > >> + >>   #ifndef __ASSEMBLY__ >>   #include >>   #include >> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c >> index 026031b3b782..83daa3f8f39c 100644 >> --- a/arch/x86/mm/ioremap.c >> +++ b/arch/x86/mm/ioremap.c >> @@ -17,6 +17,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include >> @@ -26,6 +27,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include "physaddr.h" >> @@ -87,8 +89,8 @@ static unsigned int __ioremap_check_ram(struct >> resource *res) >>   } >>   /* >> - * In a SEV guest, NONE and RESERVED should not be mapped encrypted >> because >> - * there the whole memory is already encrypted. >> + * In a SEV or TDX guest, NONE and RESERVED should not be mapped >> encrypted (or >> + * private in TDX case) because there the whole memory is already >> encrypted. >>    */ >>   static unsigned int __ioremap_check_encrypted(struct resource *res) >>   { >> @@ -246,6 +248,8 @@ __ioremap_caller(resource_size_t phys_addr, >> unsigned long size, >>       prot = PAGE_KERNEL_IO; >>       if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted) >>           prot = pgprot_encrypted(prot); >> +    else if (cc_platform_has(CC_ATTR_GUEST_SHARED_MAPPING_INIT)) >> +        prot = pgprot_cc_guest(prot); > > And if you do the new functions this could be: > >     if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted) >         prot = pgprot_private(prot); >     else >         prot = pgprot_shared(prot); Yes. I will make this change in next version. > > Thanks, > Tom > >>       switch (pcm) { >>       case _PAGE_CACHE_MODE_UC: >> diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h >> index 7728574d7783..edb1d7a2f6af 100644 >> --- a/include/linux/cc_platform.h >> +++ b/include/linux/cc_platform.h >> @@ -81,6 +81,19 @@ enum cc_attr { >>        * Examples include TDX Guest. >>        */ >>       CC_ATTR_GUEST_UNROLL_STRING_IO, >> + >> +    /** >> +     * @CC_ATTR_GUEST_SHARED_MAPPING_INIT: IO Remapped memory is marked >> +     *                       as shared. >> +     * >> +     * The platform/OS is running as a guest/virtual machine and >> +     * initializes all IO remapped memory as shared. >> +     * >> +     * Examples include TDX Guest (SEV marks all pages as shared by >> default >> +     * so this feature cannot be enabled for it). >> +     */ >> +    CC_ATTR_GUEST_SHARED_MAPPING_INIT, >> + >>   }; >>   #ifdef CONFIG_ARCH_HAS_CC_PLATFORM >> -- Sathyanarayanan Kuppuswamy Linux Kernel Developer