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    Subject[PATCH v13 09/12] mm: x86: Invoke hypercall when page encryption status is changed
    Date
    From: Brijesh Singh <brijesh.singh@amd.com>

    Invoke a hypercall when a memory region is changed from encrypted ->
    decrypted and vice versa. Hypervisor needs 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: 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
    Reviewed-by: Steve Rutherford <srutherford@google.com>
    Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
    ---
    arch/x86/include/asm/paravirt.h | 10 +++++
    arch/x86/include/asm/paravirt_types.h | 2 +
    arch/x86/kernel/paravirt.c | 1 +
    arch/x86/mm/mem_encrypt.c | 57 ++++++++++++++++++++++++++-
    arch/x86/mm/pat/set_memory.c | 7 ++++
    5 files changed, 76 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
    index 4abf110e2243..efaa3e628967 100644
    --- a/arch/x86/include/asm/paravirt.h
    +++ b/arch/x86/include/asm/paravirt.h
    @@ -84,6 +84,12 @@ static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
    PVOP_VCALL1(mmu.exit_mmap, mm);
    }

    +static inline void page_encryption_changed(unsigned long vaddr, int npages,
    + bool enc)
    +{
    + PVOP_VCALL3(mmu.page_encryption_changed, vaddr, npages, enc);
    +}
    +
    #ifdef CONFIG_PARAVIRT_XXL
    static inline void load_sp0(unsigned long sp0)
    {
    @@ -799,6 +805,10 @@ static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm,
    static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
    {
    }
    +
    +static inline void page_encryption_changed(unsigned long vaddr, int npages, bool enc)
    +{
    +}
    #endif
    #endif /* __ASSEMBLY__ */
    #endif /* _ASM_X86_PARAVIRT_H */
    diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
    index de87087d3bde..69ef9c207b38 100644
    --- a/arch/x86/include/asm/paravirt_types.h
    +++ b/arch/x86/include/asm/paravirt_types.h
    @@ -195,6 +195,8 @@ struct pv_mmu_ops {

    /* Hook for intercepting the destruction of an mm_struct. */
    void (*exit_mmap)(struct mm_struct *mm);
    + void (*page_encryption_changed)(unsigned long vaddr, int npages,
    + bool enc);

    #ifdef CONFIG_PARAVIRT_XXL
    struct paravirt_callee_save read_cr2;
    diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
    index c60222ab8ab9..9f206e192f6b 100644
    --- a/arch/x86/kernel/paravirt.c
    +++ b/arch/x86/kernel/paravirt.c
    @@ -335,6 +335,7 @@ struct paravirt_patch_template pv_ops = {
    (void (*)(struct mmu_gather *, void *))tlb_remove_page,

    .mmu.exit_mmap = paravirt_nop,
    + .mmu.page_encryption_changed = paravirt_nop,

    #ifdef CONFIG_PARAVIRT_XXL
    .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2),
    diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
    index ae78cef79980..fae9ccbd0da7 100644
    --- a/arch/x86/mm/mem_encrypt.c
    +++ b/arch/x86/mm/mem_encrypt.c
    @@ -19,6 +19,7 @@
    #include <linux/kernel.h>
    #include <linux/bitops.h>
    #include <linux/dma-mapping.h>
    +#include <linux/kvm_para.h>

    #include <asm/tlbflush.h>
    #include <asm/fixmap.h>
    @@ -29,6 +30,7 @@
    #include <asm/processor-flags.h>
    #include <asm/msr.h>
    #include <asm/cmdline.h>
    +#include <asm/kvm_para.h>

    #include "mm_internal.h"

    @@ -229,6 +231,47 @@ void __init sev_setup_arch(void)
    swiotlb_adjust_size(size);
    }

    +static void set_memory_enc_dec_hypercall(unsigned long vaddr, int npages,
    + bool enc)
    +{
    + unsigned long sz = npages << PAGE_SHIFT;
    + 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;
    @@ -286,12 +329,13 @@ 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;

    @@ -346,6 +390,8 @@ static int __init early_set_memory_enc_dec(unsigned long vaddr,

    ret = 0;

    + set_memory_enc_dec_hypercall(start, PAGE_ALIGN(size) >> PAGE_SHIFT,
    + enc);
    out:
    __flush_tlb_all();
    return ret;
    @@ -481,6 +527,15 @@ void __init mem_encrypt_init(void)
    if (sev_active() && !sev_es_active())
    static_branch_enable(&sev_enable_key);

    +#ifdef CONFIG_PARAVIRT
    + /*
    + * With SEV, we need to make a hypercall when page encryption state is
    + * changed.
    + */
    + if (sev_active())
    + pv_ops.mmu.page_encryption_changed = set_memory_enc_dec_hypercall;
    +#endif
    +
    print_mem_encrypt_feature_info();
    }

    diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
    index 16f878c26667..3576b583ac65 100644
    --- a/arch/x86/mm/pat/set_memory.c
    +++ b/arch/x86/mm/pat/set_memory.c
    @@ -27,6 +27,7 @@
    #include <asm/proto.h>
    #include <asm/memtype.h>
    #include <asm/set_memory.h>
    +#include <asm/paravirt.h>

    #include "../mm_internal.h"

    @@ -2012,6 +2013,12 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
    */
    cpa_flush(&cpa, 0);

    + /* Notify hypervisor that a given memory range is mapped encrypted
    + * or decrypted. The hypervisor will use this information during the
    + * VM migration.
    + */
    + page_encryption_changed(addr, numpages, enc);
    +
    return ret;
    }

    --
    2.17.1
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