From: Andi Kleen <ak@xxxxxxxxxxxxxxx> Implement ioremap_host_shared for x86. In TDX most memory is encrypted, but some memory that is used to communicate with the host must be declared shared with special page table attributes and a special hypercall. Previously all ioremaped memory was declared shared, but this leads to various BIOS tables and other private state being shared, which is a security risk. This patch replaces the unconditional ioremap sharing with an explicit ioremap_host_shared that enables sharing. Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> --- Changes since v4: * Rebased on top of Tom Lendacky's CC guest changes (https://www.spinics.net/lists/linux-tip-commits/msg58716.html) arch/x86/include/asm/io.h | 4 ++++ arch/x86/mm/ioremap.c | 41 ++++++++++++++++++++++++++++++--------- 2 files changed, 36 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 67e0c4a0a0f4..521b239c013f 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -380,6 +380,10 @@ extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size); extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size); #define ioremap_wt ioremap_wt +extern void __iomem *ioremap_host_shared(resource_size_t offset, + unsigned long size); +#define ioremap_host_shared ioremap_host_shared + extern bool is_early_ioremap_ptep(pte_t *ptep); #define IO_SPACE_LIMIT 0xffff diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 83daa3f8f39c..a83a69045f61 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -178,7 +178,8 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size, */ static void __iomem * __ioremap_caller(resource_size_t phys_addr, unsigned long size, - enum page_cache_mode pcm, void *caller, bool encrypted) + enum page_cache_mode pcm, void *caller, bool encrypted, + bool shared) { unsigned long offset, vaddr; resource_size_t last_addr; @@ -248,7 +249,7 @@ __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)) + else if (shared) prot = pgprot_cc_guest(prot); switch (pcm) { @@ -340,7 +341,8 @@ void __iomem *ioremap(resource_size_t phys_addr, unsigned long size) enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC_MINUS; return __ioremap_caller(phys_addr, size, pcm, - __builtin_return_address(0), false); + __builtin_return_address(0), false, + false); } EXPORT_SYMBOL(ioremap); @@ -373,7 +375,8 @@ void __iomem *ioremap_uc(resource_size_t phys_addr, unsigned long size) enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC; return __ioremap_caller(phys_addr, size, pcm, - __builtin_return_address(0), false); + __builtin_return_address(0), false, + false); } EXPORT_SYMBOL_GPL(ioremap_uc); @@ -390,10 +393,29 @@ EXPORT_SYMBOL_GPL(ioremap_uc); void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size) { return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC, - __builtin_return_address(0), false); + __builtin_return_address(0), false, + false); } EXPORT_SYMBOL(ioremap_wc); +/** + * ioremap_host_shared - map memory into CPU space shared with host + * @phys_addr: bus address of the memory + * @size: size of the resource to map + * + * This version of ioremap ensures that the memory is marked shared + * with the host. This is useful for confidential guests. + * + * Must be freed with iounmap. + */ +void __iomem *ioremap_host_shared(resource_size_t phys_addr, unsigned long size) +{ + return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_UC, + __builtin_return_address(0), false, + cc_platform_has(CC_ATTR_GUEST_SHARED_MAPPING_INIT)); +} +EXPORT_SYMBOL(ioremap_host_shared); + /** * ioremap_wt - map memory into CPU space write through * @phys_addr: bus address of the memory @@ -407,21 +429,22 @@ EXPORT_SYMBOL(ioremap_wc); void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size) { return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT, - __builtin_return_address(0), false); + __builtin_return_address(0), false, + false); } EXPORT_SYMBOL(ioremap_wt); void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size) { return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB, - __builtin_return_address(0), true); + __builtin_return_address(0), true, false); } EXPORT_SYMBOL(ioremap_encrypted); void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size) { return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB, - __builtin_return_address(0), false); + __builtin_return_address(0), false, false); } EXPORT_SYMBOL(ioremap_cache); @@ -430,7 +453,7 @@ void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size, { return __ioremap_caller(phys_addr, size, pgprot2cachemode(__pgprot(prot_val)), - __builtin_return_address(0), false); + __builtin_return_address(0), false, false); } EXPORT_SYMBOL(ioremap_prot); -- 2.25.1
