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Message-ID: <20230531122510.3vthiyearwkyqrwf@box.shutemov.name>
Date: Wed, 31 May 2023 15:25:10 +0300
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Isaku Yamahata <isaku.yamahata@...il.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...el.com>,
Sean Christopherson <seanjc@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Joerg Roedel <jroedel@...e.de>,
Ard Biesheuvel <ardb@...nel.org>,
Andi Kleen <ak@...ux.intel.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Tom Lendacky <thomas.lendacky@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
Dario Faggioli <dfaggioli@...e.com>,
Mike Rapoport <rppt@...nel.org>,
David Hildenbrand <david@...hat.com>,
Mel Gorman <mgorman@...hsingularity.net>,
marcelo.cerri@...onical.com, tim.gardner@...onical.com,
khalid.elmously@...onical.com, philip.cox@...onical.com,
aarcange@...hat.com, peterx@...hat.com, x86@...nel.org,
linux-mm@...ck.org, linux-coco@...ts.linux.dev,
linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv12 9/9] x86/tdx: Add unaccepted memory support
On Tue, May 30, 2023 at 05:58:37PM -0700, Isaku Yamahata wrote:
> On Fri, May 19, 2023 at 02:14:34AM +0300,
> "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> wrote:
>
> > Hookup TDX-specific code to accept memory.
> >
> > Accepting the memory is the same process as converting memory from
> > shared to private: kernel notifies VMM with MAP_GPA hypercall and then
> > accept pages with ACCEPT_PAGE module call.
> >
> > THE implementation in core kernel uses tdx_enc_status_changed(). It
> > already used for converting memory to shared and back for I/O
> > transactions.
>
> Because unaccepted memory reported in e820 means private[1], MAP_GPA isn't
> needed to accept memory. (Or are you seeing TDX KVM/qemu issue?)
>
> [1]TDX Virtual Firmware Design Guide.
> 7.2.1 Memroy Type in TD Resrouce HOB. Table 7-1: Mmeory Typein TD Resource HOB.
Okay. Fair enough. We can avoid a MAP_GPA and cut cost of memory
acceptance.
Here's an updated patch:
>From 8b3deddeef639ab7e05d3359dd97ee7994978751 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Date: Wed, 25 Aug 2021 21:42:53 +0300
Subject: [PATCHv12.1 9/9] x86/tdx: Add unaccepted memory support
Hookup TDX-specific code to accept memory.
Accepting the memory is done with ACCEPT_PAGE module call on every page
in the range. MAP_GPA hypercall is not required as the unaccepted memory
is considered private already.
Extract the part of tdx_enc_status_changed() that does memory acceptance
in a new helper. Move the helper tdx-shared.c. It is going to be used by
both main kernel and decompressor.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
arch/x86/Kconfig | 2 +
arch/x86/boot/compressed/Makefile | 2 +-
arch/x86/boot/compressed/error.c | 19 +++++++
arch/x86/boot/compressed/error.h | 1 +
arch/x86/boot/compressed/mem.c | 35 +++++++++++-
arch/x86/boot/compressed/tdx-shared.c | 2 +
arch/x86/coco/tdx/Makefile | 2 +-
arch/x86/coco/tdx/tdx-shared.c | 71 ++++++++++++++++++++++++
arch/x86/coco/tdx/tdx.c | 70 +----------------------
arch/x86/include/asm/shared/tdx.h | 2 +
arch/x86/include/asm/unaccepted_memory.h | 24 ++++++++
11 files changed, 160 insertions(+), 70 deletions(-)
create mode 100644 arch/x86/boot/compressed/tdx-shared.c
create mode 100644 arch/x86/coco/tdx/tdx-shared.c
create mode 100644 arch/x86/include/asm/unaccepted_memory.h
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee..5c72067c06d4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -884,9 +884,11 @@ config INTEL_TDX_GUEST
bool "Intel TDX (Trust Domain Extensions) - Guest Support"
depends on X86_64 && CPU_SUP_INTEL
depends on X86_X2APIC
+ depends on EFI_STUB
select ARCH_HAS_CC_PLATFORM
select X86_MEM_ENCRYPT
select X86_MCE
+ select UNACCEPTED_MEMORY
help
Support running as a guest under Intel TDX. Without this support,
the guest kernel can not boot or run under TDX.
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index cc4978123c30..b13a58021086 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -106,7 +106,7 @@ ifdef CONFIG_X86_64
endif
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
-vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o
+vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o $(obj)/tdx-shared.o
vmlinux-objs-$(CONFIG_UNACCEPTED_MEMORY) += $(obj)/mem.o
vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
diff --git a/arch/x86/boot/compressed/error.c b/arch/x86/boot/compressed/error.c
index c881878e56d3..5313c5cb2b80 100644
--- a/arch/x86/boot/compressed/error.c
+++ b/arch/x86/boot/compressed/error.c
@@ -22,3 +22,22 @@ void error(char *m)
while (1)
asm("hlt");
}
+
+/* EFI libstub provides vsnprintf() */
+#ifdef CONFIG_EFI_STUB
+void panic(const char *fmt, ...)
+{
+ static char buf[1024];
+ va_list args;
+ int len;
+
+ va_start(args, fmt);
+ len = vsnprintf(buf, sizeof(buf), fmt, args);
+ va_end(args);
+
+ if (len && buf[len - 1] == '\n')
+ buf[len - 1] = '\0';
+
+ error(buf);
+}
+#endif
diff --git a/arch/x86/boot/compressed/error.h b/arch/x86/boot/compressed/error.h
index 1de5821184f1..86fe33b93715 100644
--- a/arch/x86/boot/compressed/error.h
+++ b/arch/x86/boot/compressed/error.h
@@ -6,5 +6,6 @@
void warn(char *m);
void error(char *m) __noreturn;
+void panic(const char *fmt, ...) __noreturn __cold;
#endif /* BOOT_COMPRESSED_ERROR_H */
diff --git a/arch/x86/boot/compressed/mem.c b/arch/x86/boot/compressed/mem.c
index 4ecf26576a77..d2b6948a7801 100644
--- a/arch/x86/boot/compressed/mem.c
+++ b/arch/x86/boot/compressed/mem.c
@@ -2,11 +2,44 @@
#include "error.h"
#include "misc.h"
+#include "tdx.h"
+#include <asm/shared/tdx.h>
+
+/*
+ * accept_memory() and process_unaccepted_memory() called from EFI stub which
+ * runs before decompresser and its early_tdx_detect().
+ *
+ * Enumerate TDX directly from the early users.
+ */
+static bool early_is_tdx_guest(void)
+{
+ static bool once;
+ static bool is_tdx;
+
+ if (!IS_ENABLED(CONFIG_INTEL_TDX_GUEST))
+ return false;
+
+ if (!once) {
+ u32 eax, sig[3];
+
+ cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax,
+ &sig[0], &sig[2], &sig[1]);
+ is_tdx = !memcmp(TDX_IDENT, sig, sizeof(sig));
+ once = true;
+ }
+
+ return is_tdx;
+}
void arch_accept_memory(phys_addr_t start, phys_addr_t end)
{
/* Platform-specific memory-acceptance call goes here */
- error("Cannot accept memory");
+ if (early_is_tdx_guest()) {
+ if (tdx_accept_memory(start, end))
+ return;
+ }
+
+ error("Cannot accept memory: unknown platform\n");
}
void init_unaccepted_memory(void)
diff --git a/arch/x86/boot/compressed/tdx-shared.c b/arch/x86/boot/compressed/tdx-shared.c
new file mode 100644
index 000000000000..5ac43762fe13
--- /dev/null
+++ b/arch/x86/boot/compressed/tdx-shared.c
@@ -0,0 +1,2 @@
+#include "error.h"
+#include "../../coco/tdx/tdx-shared.c"
diff --git a/arch/x86/coco/tdx/Makefile b/arch/x86/coco/tdx/Makefile
index 46c55998557d..2c7dcbf1458b 100644
--- a/arch/x86/coco/tdx/Makefile
+++ b/arch/x86/coco/tdx/Makefile
@@ -1,3 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
-obj-y += tdx.o tdcall.o
+obj-y += tdx.o tdx-shared.o tdcall.o
diff --git a/arch/x86/coco/tdx/tdx-shared.c b/arch/x86/coco/tdx/tdx-shared.c
new file mode 100644
index 000000000000..ef20ddc37b58
--- /dev/null
+++ b/arch/x86/coco/tdx/tdx-shared.c
@@ -0,0 +1,71 @@
+#include <asm/tdx.h>
+#include <asm/pgtable.h>
+
+static unsigned long try_accept_one(phys_addr_t start, unsigned long len,
+ enum pg_level pg_level)
+{
+ unsigned long accept_size = page_level_size(pg_level);
+ u64 tdcall_rcx;
+ u8 page_size;
+
+ if (!IS_ALIGNED(start, accept_size))
+ return 0;
+
+ if (len < accept_size)
+ return 0;
+
+ /*
+ * Pass the page physical address to the TDX module to accept the
+ * pending, private page.
+ *
+ * Bits 2:0 of RCX encode page size: 0 - 4K, 1 - 2M, 2 - 1G.
+ */
+ switch (pg_level) {
+ case PG_LEVEL_4K:
+ page_size = 0;
+ break;
+ case PG_LEVEL_2M:
+ page_size = 1;
+ break;
+ case PG_LEVEL_1G:
+ page_size = 2;
+ break;
+ default:
+ return 0;
+ }
+
+ tdcall_rcx = start | page_size;
+ if (__tdx_module_call(TDX_ACCEPT_PAGE, tdcall_rcx, 0, 0, 0, NULL))
+ return 0;
+
+ return accept_size;
+}
+
+bool tdx_accept_memory(phys_addr_t start, phys_addr_t end)
+{
+ /*
+ * For shared->private conversion, accept the page using
+ * TDX_ACCEPT_PAGE TDX module call.
+ */
+ while (start < end) {
+ unsigned long len = end - start;
+ unsigned long accept_size;
+
+ /*
+ * Try larger accepts first. It gives chance to VMM to keep
+ * 1G/2M Secure EPT entries where possible and speeds up
+ * process by cutting number of hypercalls (if successful).
+ */
+
+ accept_size = try_accept_one(start, len, PG_LEVEL_1G);
+ if (!accept_size)
+ accept_size = try_accept_one(start, len, PG_LEVEL_2M);
+ if (!accept_size)
+ accept_size = try_accept_one(start, len, PG_LEVEL_4K);
+ if (!accept_size)
+ return false;
+ start += accept_size;
+ }
+
+ return true;
+}
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 0d5fe6e24e45..a9c4ba6c5c5d 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -713,46 +713,6 @@ static bool tdx_cache_flush_required(void)
return true;
}
-static unsigned long try_accept_one(phys_addr_t start, unsigned long len,
- enum pg_level pg_level)
-{
- unsigned long accept_size = page_level_size(pg_level);
- u64 tdcall_rcx;
- u8 page_size;
-
- if (!IS_ALIGNED(start, accept_size))
- return 0;
-
- if (len < accept_size)
- return 0;
-
- /*
- * Pass the page physical address to the TDX module to accept the
- * pending, private page.
- *
- * Bits 2:0 of RCX encode page size: 0 - 4K, 1 - 2M, 2 - 1G.
- */
- switch (pg_level) {
- case PG_LEVEL_4K:
- page_size = 0;
- break;
- case PG_LEVEL_2M:
- page_size = 1;
- break;
- case PG_LEVEL_1G:
- page_size = 2;
- break;
- default:
- return 0;
- }
-
- tdcall_rcx = start | page_size;
- if (__tdx_module_call(TDX_ACCEPT_PAGE, tdcall_rcx, 0, 0, 0, NULL))
- return 0;
-
- return accept_size;
-}
-
/*
* Inform the VMM of the guest's intent for this physical page: shared with
* the VMM or private to the guest. The VMM is expected to change its mapping
@@ -777,33 +737,9 @@ static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc)
if (_tdx_hypercall(TDVMCALL_MAP_GPA, start, end - start, 0, 0))
return false;
- /* private->shared conversion requires only MapGPA call */
- if (!enc)
- return true;
-
- /*
- * For shared->private conversion, accept the page using
- * TDX_ACCEPT_PAGE TDX module call.
- */
- while (start < end) {
- unsigned long len = end - start;
- unsigned long accept_size;
-
- /*
- * Try larger accepts first. It gives chance to VMM to keep
- * 1G/2M Secure EPT entries where possible and speeds up
- * process by cutting number of hypercalls (if successful).
- */
-
- accept_size = try_accept_one(start, len, PG_LEVEL_1G);
- if (!accept_size)
- accept_size = try_accept_one(start, len, PG_LEVEL_2M);
- if (!accept_size)
- accept_size = try_accept_one(start, len, PG_LEVEL_4K);
- if (!accept_size)
- return false;
- start += accept_size;
- }
+ /* shared->private conversion requires memory to be accepted before use */
+ if (enc)
+ return tdx_accept_memory(start, end);
return true;
}
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 1ff0ee822961..19228beb4894 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -91,5 +91,7 @@ struct tdx_module_output {
u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
struct tdx_module_output *out);
+bool tdx_accept_memory(phys_addr_t start, phys_addr_t end);
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_SHARED_TDX_H */
diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/asm/unaccepted_memory.h
new file mode 100644
index 000000000000..f0ab217b566f
--- /dev/null
+++ b/arch/x86/include/asm/unaccepted_memory.h
@@ -0,0 +1,24 @@
+#ifndef _ASM_X86_UNACCEPTED_MEMORY_H
+#define _ASM_X86_UNACCEPTED_MEMORY_H
+
+#include <linux/efi.h>
+#include <asm/tdx.h>
+
+static inline void arch_accept_memory(phys_addr_t start, phys_addr_t end)
+{
+ /* Platform-specific memory-acceptance call goes here */
+ if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
+ if (tdx_accept_memory(start, end))
+ return;
+ }
+
+ panic("Cannot accept memory: unknown platform\n");
+}
+
+static inline struct efi_unaccepted_memory *efi_get_unaccepted_table(void)
+{
+ if (efi.unaccepted == EFI_INVALID_TABLE_ADDR)
+ return NULL;
+ return __va(efi.unaccepted);
+}
+#endif
--
Kiryl Shutsemau / Kirill A. Shutemov
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