Tom Lendacky
2021-Oct-20 16:39 UTC
[PATCH v5 07/16] x86/kvm: Use bounce buffers for TD guest
On 10/8/21 7:37 PM, Kuppuswamy Sathyanarayanan wrote:> From: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com> > > Intel TDX doesn't allow VMM to directly access guest private memory. > Any memory that is required for communication with VMM must be shared > explicitly. The same rule applies for any DMA to and from TDX guest. > All DMA pages had to marked as shared pages. A generic way to achieve > this without any changes to device drivers is to use the SWIOTLB > framework. > > This method of handling is similar to AMD SEV. So extend this support > for TDX guest as well. Also since there are some common code between > AMD SEV and TDX guest in mem_encrypt_init(), move it to > mem_encrypt_common.c and call AMD specific init function from it > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com> > Reviewed-by: Andi Kleen <ak at linux.intel.com> > Reviewed-by: Tony Luck <tony.luck at intel.com> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com> > --- > > Changes since v4: > * Replaced prot_guest_has() with cc_guest_has(). > > Changes since v3: > * Rebased on top of Tom Lendacky's protected guest > changes (https://lore.kernel.org/patchwork/cover/1468760/) > > Changes since v1: > * Removed sme_me_mask check for amd_mem_encrypt_init() in mem_encrypt_init(). > > arch/x86/include/asm/mem_encrypt_common.h | 3 +++ > arch/x86/kernel/tdx.c | 2 ++ > arch/x86/mm/mem_encrypt.c | 5 +---- > arch/x86/mm/mem_encrypt_common.c | 14 ++++++++++++++ > 4 files changed, 20 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/mem_encrypt_common.h b/arch/x86/include/asm/mem_encrypt_common.h > index 697bc40a4e3d..bc90e565bce4 100644 > --- a/arch/x86/include/asm/mem_encrypt_common.h > +++ b/arch/x86/include/asm/mem_encrypt_common.h > @@ -8,11 +8,14 @@ > > #ifdef CONFIG_AMD_MEM_ENCRYPT > bool amd_force_dma_unencrypted(struct device *dev); > +void __init amd_mem_encrypt_init(void); > #else /* CONFIG_AMD_MEM_ENCRYPT */ > static inline bool amd_force_dma_unencrypted(struct device *dev) > { > return false; > } > + > +static inline void amd_mem_encrypt_init(void) {} > #endif /* CONFIG_AMD_MEM_ENCRYPT */ > > #endif > diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c > index 433f366ca25c..ce8e3019b812 100644 > --- a/arch/x86/kernel/tdx.c > +++ b/arch/x86/kernel/tdx.c > @@ -12,6 +12,7 @@ > #include <asm/insn.h> > #include <asm/insn-eval.h> > #include <linux/sched/signal.h> /* force_sig_fault() */ > +#include <linux/swiotlb.h> > > /* TDX Module call Leaf IDs */ > #define TDX_GET_INFO 1 > @@ -577,6 +578,7 @@ void __init tdx_early_init(void) > pv_ops.irq.halt = tdx_halt; > > legacy_pic = &null_legacy_pic; > + swiotlb_force = SWIOTLB_FORCE; > > cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "tdx:cpu_hotplug", > NULL, tdx_cpu_offline_prepare); > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > index 5d7fbed73949..8385bc4565e9 100644 > --- a/arch/x86/mm/mem_encrypt.c > +++ b/arch/x86/mm/mem_encrypt.c > @@ -438,14 +438,11 @@ static void print_mem_encrypt_feature_info(void) > } > > /* Architecture __weak replacement functions */ > -void __init mem_encrypt_init(void) > +void __init amd_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, > * but SEV-ES supports them through the #VC handler. > diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c > index 119a9056efbb..6fe44c6cb753 100644 > --- a/arch/x86/mm/mem_encrypt_common.c > +++ b/arch/x86/mm/mem_encrypt_common.c > @@ -10,6 +10,7 @@ > #include <asm/mem_encrypt_common.h> > #include <linux/dma-mapping.h> > #include <linux/cc_platform.h> > +#include <linux/swiotlb.h> > > /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ > bool force_dma_unencrypted(struct device *dev) > @@ -24,3 +25,16 @@ bool force_dma_unencrypted(struct device *dev) > > return false; > } > + > +/* Architecture __weak replacement functions */ > +void __init mem_encrypt_init(void) > +{ > + /* > + * For TDX guest or SEV/SME, call into SWIOTLB to update > + * the SWIOTLB DMA buffers > + */ > + if (sme_me_mask || cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))Can't you just make this: if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) SEV will return true if sme_me_mask is not zero and TDX should only return true if it is TDX guest, right? Thanks, Tom> + swiotlb_update_mem_attributes(); > + > + amd_mem_encrypt_init(); > +} >