[RFCv2 04/13] x86/kvm: Use bounce buffers for KVM memory protection

Kirill A. Shutemov
2021-04-16T15:41:48Z

Mirror SEV, use SWIOTLB always if KVM memory protection is enabled.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/mem_encrypt.h | 7 +++--
arch/x86/kernel/kvm.c | 2 ++
arch/x86/kernel/pci-swiotlb.c | 3 +-
arch/x86/mm/mem_encrypt.c | 44 ---------------------------
arch/x86/mm/mem_encrypt_common.c | 48 ++++++++++++++++++++++++++++++
6 files changed, 57 insertions(+), 48 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d197b3beb904..c51d14db5620 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -812,6 +812,7 @@ config KVM_GUEST
select ARCH_CPUIDLE_HALTPOLL
select X86_HV_CALLBACK_VECTOR
select X86_MEM_ENCRYPT_COMMON
+ select SWIOTLB
default y
help
This option enables various optimizations for running under the KVM
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 31c4df123aa0..a748b30c2f23 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -47,10 +47,8 @@ int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size);

void __init mem_encrypt_free_decrypted_mem(void);

-/* Architecture __weak replacement functions */
-void __init mem_encrypt_init(void);
-
void __init sev_es_init_vc_handling(void);
+
bool sme_active(void);
bool sev_active(void);
bool sev_es_active(void);
@@ -91,6 +89,9 @@ static inline void mem_encrypt_free_decrypted_mem(void) { }

#endif /* CONFIG_AMD_MEM_ENCRYPT */

+/* Architecture __weak replacement functions */
+void __init mem_encrypt_init(void);
+
/*
* The __sme_pa() and __sme_pa_nodebug() macros are meant for use when
* writing to or comparing values from the cr3 register. Having the
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index aed6034fcac1..ba179f5ca198 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -26,6 +26,7 @@
#include <linux/kprobes.h>
#include <linux/nmi.h>
#include <linux/swait.h>
+#include <linux/swiotlb.h>
#include <asm/timer.h>
#include <asm/cpu.h>
#include <asm/traps.h>
@@ -765,6 +766,7 @@ static void __init kvm_init_platform(void)
pr_info("KVM memory protection enabled\n");
mem_protected = true;
setup_force_cpu_cap(X86_FEATURE_KVM_MEM_PROTECTED);
+ swiotlb_force = SWIOTLB_FORCE;
}
}

diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index c2cfa5e7c152..814060a6ceb0 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -13,6 +13,7 @@
#include <asm/dma.h>
#include <asm/xen/swiotlb-xen.h>
#include <asm/iommu_table.h>
+#include <asm/kvm_para.h>

int swiotlb __read_mostly;

@@ -49,7 +50,7 @@ int __init pci_swiotlb_detect_4gb(void)
* buffers are allocated and used for devices that do not support
* the addressing range required for the encryption mask.
*/
- if (sme_active())
+ if (sme_active() || kvm_mem_protected())
swiotlb = 1;

return swiotlb;
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 9ca477b9b8ba..3478f20fb46f 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -409,47 +409,3 @@ void __init mem_encrypt_free_decrypted_mem(void)

free_init_pages("unused decrypted", vaddr, vaddr_end);
}
-
-static void print_mem_encrypt_feature_info(void)
-{
- pr_info("AMD Memory Encryption Features active:");
-
- /* Secure Memory Encryption */
- if (sme_active()) {
- /*
- * SME is mutually exclusive with any of the SEV
- * features below.
- */
- pr_cont(" SME\n");
- return;
- }
-
- /* Secure Encrypted Virtualization */
- if (sev_active())
- pr_cont(" SEV");
-
- /* Encrypted Register State */
- if (sev_es_active())
- pr_cont(" SEV-ES");
-
- pr_cont("\n");
-}
-
-/* Architecture __weak replacement functions */
-void __init mem_encrypt_init(void)
-{
- if (!sme_me_mask)
- return;
-
- /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
- swiotlb_update_mem_attributes();
-
- /*
- * With SEV, we need to unroll the rep string I/O instructions.
- */
- if (sev_active())
- static_branch_enable(&sev_enable_key);
-
- print_mem_encrypt_feature_info();
-}
-
diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
index 6bf0718bb72a..351b77361a5d 100644
--- a/arch/x86/mm/mem_encrypt_common.c
+++ b/arch/x86/mm/mem_encrypt_common.c
@@ -11,6 +11,7 @@
#include <linux/mem_encrypt.h>
#include <linux/dma-direct.h>
#include <asm/kvm_para.h>
+#include <asm/mem_encrypt.h>

/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
@@ -37,3 +38,50 @@ bool force_dma_unencrypted(struct device *dev)

return false;
}
+
+static void print_mem_encrypt_feature_info(void)
+{
+ if (kvm_mem_protected()) {
+ pr_info("KVM memory protection enabled\n");
+ return;
+ }
+
+ pr_info("AMD Memory Encryption Features active:");
+
+ /* Secure Memory Encryption */
+ if (sme_active()) {
+ /*
+ * SME is mutually exclusive with any of the SEV
+ * features below.
+ */
+ pr_cont(" SME\n");
+ return;
+ }
+
+ /* Secure Encrypted Virtualization */
+ if (sev_active())
+ pr_cont(" SEV");
+
+ /* Encrypted Register State */
+ if (sev_es_active())
+ pr_cont(" SEV-ES");
+
+ pr_cont("\n");
+}
+
+void __init mem_encrypt_init(void)
+{
+ if (!sme_me_mask && !kvm_mem_protected())
+ return;
+
+ /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
+ swiotlb_update_mem_attributes();
+
+ /*
+ * With SEV, we need to unroll the rep string I/O instructions.
+ */
+ if (sev_active())
+ static_branch_enable(&sev_enable_key);
+
+ print_mem_encrypt_feature_info();
+}
--
2.26.3