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    Subject[PATCH v3 10/11] mm: x86: Invoke hypercall when page encryption status is changed
    Date
    Invoke a hypercall when a memory region is changed from encrypted ->
    decrypted and vice versa. Hypervisor need to know the page encryption
    status during the guest migration.

    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: "Radim Krčmář" <rkrcmar@redhat.com>
    Cc: Joerg Roedel <joro@8bytes.org>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: x86@kernel.org
    Cc: kvm@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    ---
    arch/x86/include/asm/mem_encrypt.h | 3 ++
    arch/x86/mm/mem_encrypt.c | 45 +++++++++++++++++++++++++++++-
    arch/x86/mm/pageattr.c | 15 ++++++++++
    3 files changed, 62 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
    index 0c196c47d621..6e654ab5a8e4 100644
    --- a/arch/x86/include/asm/mem_encrypt.h
    +++ b/arch/x86/include/asm/mem_encrypt.h
    @@ -94,4 +94,7 @@ extern char __start_bss_decrypted[], __end_bss_decrypted[], __start_bss_decrypte

    #endif /* __ASSEMBLY__ */

    +extern void set_memory_enc_dec_hypercall(unsigned long vaddr,
    + unsigned long size, bool enc);
    +
    #endif /* __X86_MEM_ENCRYPT_H__ */
    diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
    index e0df96fdfe46..f3fda1de2869 100644
    --- a/arch/x86/mm/mem_encrypt.c
    +++ b/arch/x86/mm/mem_encrypt.c
    @@ -15,6 +15,7 @@
    #include <linux/dma-direct.h>
    #include <linux/swiotlb.h>
    #include <linux/mem_encrypt.h>
    +#include <linux/kvm_para.h>

    #include <asm/tlbflush.h>
    #include <asm/fixmap.h>
    @@ -25,6 +26,7 @@
    #include <asm/processor-flags.h>
    #include <asm/msr.h>
    #include <asm/cmdline.h>
    +#include <asm/kvm_para.h>

    #include "mm_internal.h"

    @@ -192,6 +194,45 @@ void __init sme_early_init(void)
    swiotlb_force = SWIOTLB_FORCE;
    }

    +void set_memory_enc_dec_hypercall(unsigned long vaddr, unsigned long sz, bool enc)
    +{
    + unsigned long vaddr_end, vaddr_next;
    +
    + vaddr_end = vaddr + sz;
    +
    + for (; vaddr < vaddr_end; vaddr = vaddr_next) {
    + int psize, pmask, level;
    + unsigned long pfn;
    + pte_t *kpte;
    +
    + kpte = lookup_address(vaddr, &level);
    + if (!kpte || pte_none(*kpte))
    + return;
    +
    + switch (level) {
    + case PG_LEVEL_4K:
    + pfn = pte_pfn(*kpte);
    + break;
    + case PG_LEVEL_2M:
    + pfn = pmd_pfn(*(pmd_t *)kpte);
    + break;
    + case PG_LEVEL_1G:
    + pfn = pud_pfn(*(pud_t *)kpte);
    + break;
    + default:
    + return;
    + }
    +
    + psize = page_level_size(level);
    + pmask = page_level_mask(level);
    +
    + kvm_sev_hypercall3(KVM_HC_PAGE_ENC_STATUS,
    + pfn << PAGE_SHIFT, psize >> PAGE_SHIFT, enc);
    +
    + vaddr_next = (vaddr & pmask) + psize;
    + }
    +}
    +
    static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
    {
    pgprot_t old_prot, new_prot;
    @@ -249,12 +290,13 @@ static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
    static int __init early_set_memory_enc_dec(unsigned long vaddr,
    unsigned long size, bool enc)
    {
    - unsigned long vaddr_end, vaddr_next;
    + unsigned long vaddr_end, vaddr_next, start;
    unsigned long psize, pmask;
    int split_page_size_mask;
    int level, ret;
    pte_t *kpte;

    + start = vaddr;
    vaddr_next = vaddr;
    vaddr_end = vaddr + size;

    @@ -309,6 +351,7 @@ static int __init early_set_memory_enc_dec(unsigned long vaddr,

    ret = 0;

    + set_memory_enc_dec_hypercall(start, size, enc);
    out:
    __flush_tlb_all();
    return ret;
    diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
    index 6a9a77a403c9..971f70f58f49 100644
    --- a/arch/x86/mm/pageattr.c
    +++ b/arch/x86/mm/pageattr.c
    @@ -26,6 +26,7 @@
    #include <asm/proto.h>
    #include <asm/pat.h>
    #include <asm/set_memory.h>
    +#include <asm/mem_encrypt.h>

    #include "mm_internal.h"

    @@ -2020,6 +2021,12 @@ int set_memory_global(unsigned long addr, int numpages)
    __pgprot(_PAGE_GLOBAL), 0);
    }

    +void __attribute__((weak)) set_memory_enc_dec_hypercall(unsigned long addr,
    + unsigned long size,
    + bool enc)
    +{
    +}
    +
    static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
    {
    struct cpa_data cpa;
    @@ -2060,6 +2067,14 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
    */
    cpa_flush(&cpa, 0);

    + /*
    + * When SEV is active, notify hypervisor that a given memory range is mapped
    + * encrypted or decrypted. Hypervisor will use this information during
    + * the VM migration.
    + */
    + if (sev_active())
    + set_memory_enc_dec_hypercall(addr, numpages << PAGE_SHIFT, enc);
    +
    return ret;
    }

    --
    2.17.1
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